glossary of terms

 

 sjg provides you here with a basic guide to some of the terminology & abbreviations used in the field of GSM, data, ip & telecomms

 

if a term or abbr needs adding: let us know
   

Term Explanation
10base2 Ethernet &IEEE 802.3 standard for baseband LANs using thin coaxial cable & BNC connectors up to 200 meters: data speed = 10 Mbps
10baseT Ethernet standard for LANs using twisted-pair CAT5/6 cable. data speed = 10 Mbps
100baseT Ethernet standard for LANs using twisted-pair CAT5/6 cable. data speed = 100 Mbps
802.1D An IEEE standard for interLAN bridges (specifically between 802.3, 802.4 and 802.5 networks). 802.1D operates at the MAC layer
802.3 An IEEE standard for accessing a LAN using CSMA/CD. Ethernet follows this standard
802.5 An IEEE physical layer standard for a token-ring LAN access method at 4 or 16 Mbps over unshielded twisted-pair cable

A

AAL ATM adaptation layer - The layer of the ATM protocol stack that parses data into the payload portion of the ATM cell for transport across an ATM network
access control

A security mechanism that determines which operations a user, group, service, or computer is authorized to perform on a computer or on a particular object [eg a file]

ACE access control entry - An entry in an object's discretionary access control list (DACL) that grants permissions to a user or group. An ACE is also an entry in an object's system access control list (SACL) that specifies the security events to be audited for a user or group
ACPI Advanced Configuration and Power Interface - An open industry specification that defines power management on a wide range of mobile, desktop, server computers and peripherals. ACPI is the foundation for the OnNow industry initiative that allows system manufacturers to deliver computers that will start at the touch of a keyboard. ACPI design is essential to take full advantage of power management and Plug and Play
address classes

Predefined groupings of Internet addresses with each class defining networks of a certain size. The range of numbers that can be assigned for the first octet in the IP address is based on the address class

  • Class A networks (values 1 to 126) are the largest, with more than 16 million hosts per network

  • Class B networks (128 to 191) have up to 65,534 hosts per network

  • Class C networks (192 to 223) can have up to 254 hosts per network

Address resource record

A resource record used to map a DNS domain name to a host IP address on the network

administrator
  • Windows XP Professional: a person responsible for setting up & managing domain controllers or local PCs and their user and group accounts, assigning passwords and permissions, and helping users with networking problems. Administrators are members of the Administrators group and have full control over the domain or computer.

  • Windows XP Home Edition: a person who can make system-wide changes to the computer, install software, and who has access to all files on the computer. A person with a computer administrator account has full access to other user accounts on the PC

administration queue Message Queuing: a queue that stores acknowledgment messages
administrative alerts Alerts that relate to server and resource use. They notify users about problems in areas such as security and access, user sessions, server shutdown due to power loss (when an uninterruptible power supply is available), directory replication, and printing. When a computer generates an administrative alert, a message is sent to a predefined list of users and computers
active content Dynamic content, [eg news], that is usually updated from the WWW or a channel
Active Directory data model A model derived from the LDAP data model. The directory holds objects that represent entities of various sorts, described by attributes. The objects & classes of objects that can be stored in the directory are defined in the schema. For each class of objects, the schema defines the attributes an instance of the class must have, the additional attributes it can have, and the class that can be its parent
active partition

A partition from which an x86-based computer starts up. The active partition must be a primary partition on a basic disk. If you use Windows exclusively, the active partition can be the same as the system volume

active volume

The volume from which the computer starts up. The active volume must be a simple volume on a dynamic disk. You cannot mark an existing dynamic volume as the active volume, but you can upgrade a basic disk containing the active partition to a dynamic disk. Once the disk is upgraded to dynamic, the partition becomes a simple volume that is active

ActiveX

A set of technologies that allows software components to interact with one another in a networked environment, regardless of the language in which the components were created

active loop A fault condition on an IEEE 802.3 LAN in which there is more than one active route between source & destination nodes. Active loops can occur when more than one bridge is attached to the same LAN
Address ageing The process that automatically removes infrequently used dynamic MAC addresses after a configurable length of time. Separate ageing times can be configured for addresses associated with stations on the central LAN and remote LANs.
Address filtering A method of deciding which data packets are allowed through a device. The decision is based on the source and destination addresses of the data packet.
ADSL Asymmetric Digital Subscriber Line aka 'Broadband': Transports high-bandwidth data from customers [PC / LAN] and the www. The “asymmetric” term refers to the differing rates [upstream & downstream] available with ADSL. Uses existing DELs for its bearer
ADSL Bearer A DEL that also carries the ADSL [ie a fax line which also provides the ADSL service; the fax would plug in to a microfilter]
affinity Network Load Balancing: the method used to associate client requests to cluster hosts. When no affinity is specified, all network requests are load balanced across the cluster without respect to their source. Affinity is implemented by directing all client requests from the same IP address to the same cluster host
agent An application that runs on a Simple Network Management Protocol (SNMP) managed device. The agent application is the object of management activities. A computer running SNMP agent software is also sometimes referred to as an agent
AH Authentication Header - RFC2402 defines AH. AH provides integrity & authentication through the shared key hashing algorithms (HMAC-MD5, HMAC-SHA1). AH provides authentication for as much of the IP header as possible. AH also authenticates upper level protocol data.
Alerter service A service used by the server and other services to notify selected users and computers of administrative alerts that occur on a computer. The Alerter service requires the Messenger service
allocation unit aka Cluster - The smallest amount of disk space that can be allocated to hold a file. All file systems used by Windows organize hard disks based on allocation units. The smaller the allocation unit size, the more efficiently a disk stores information. If you do not specify an allocation unit size when formatting the disk, Windows picks default sizes based on the size of the volume. These default sizes are selected to reduce the amount of space that is lost and the amount of fragmentation on the volume
AM Amplitude Modulation - Modulation method used by modems, radio, and DSL equipment. The signal modulates [or alters] the amplitude or intensity of the carrier. In regular AM, the carrier is a sinewave. The amplitude of the modulated carrier changes in proportion to signal amplitude. AM creates two identical sidebands on either side of the carrier. These sidebands contain the signal data. Either sideband can be attenuated or suppressed without harming the signal data. With an equivalent signal, AM tends to require less bandwidth than FM does. AM's disadvantage is that it’s more subject to impulse noise and static than FM
Analog loopback method of testing modems & DTEs to determine line or equipment fault where the device is disconnected from the telephone line, and a signal is looped out through the receive side
API application programming interface - A set of routines that an application uses to request and carry out lower-level services performed by a computer's operating system. These routines usually carry out maintenance tasks such as managing files and displaying information.
APIPA

Automatic Private IP Addressing - A feature of Windows XP: TCP/IP that automatically configures a unique IP address from the range 169.254.0.1 through 169.254.255.254 and a subnet mask of 255.255.0.0 when the TCP/IP protocol is configured for dynamic addressing and a Dynamic Host Configuration Protocol (DHCP) is not available

AppleTalk Apple Computer network architecture and network protocols. A network that has Macintosh clients and a computer running Windows 2000 Server or Windows NT Server with Services for Macintosh functions as an AppleTalk network
AppleTalk Phase 2 The extended AppleTalk Internet model designed by Apple Computer that supports multiple zones within a network and extended addressing capacity
ASCII American Standard Code for Information Interchange - A standard coding scheme that assigns numeric values to letters, punctuation characters, control characters, and numbers to achieve compatibility among different computers and peripheral devices
  • ASCII uses designated 7-bit or 8-bit number combinations to represent either 128 or 256 possible characters. Standard ASCII uses 7 bits to represent all uppercase and lowercase letters, the numbers 0 through 9, punctuation marks, and special control characters used in U.S. English. Most current x86-based systems support the use of extended (or "high") ASCII. Extended ASCII allows the eighth bit of each character to identify an additional 128 special symbol characters, foreign-language letters, and graphic symbols
ARP             Address Resolution Protocol - A method of finding the Ethernet address of a host from its Internet address. The sender broadcasts an ARP packet containing the Internet address of a host and waits for it (or another host) to send back its Ethernet address. Each host maintains a cache of address translations to reduce delay and loading. ARP allows the Internet address to be independent of the Ethernet address, but this protocol works only if all hosts support it
  • In TCP/IP, ARP is a protocol that uses broadcast traffic on the local network to resolve a logically assigned IP address to its physical hardware or media access control layer address
  • In ATM, ARP is used two different ways. For classical IP over ATM, ARP is used to resolve addresses to ATM hardware addresses. For ATM LAN emulation, ARP is used to resolve Ethernet/802.3 or Token Ring addresses to ATM hardware addresses
ASP Application Service Provider
A.s.h.T.R.a.y Receptacle used for depositing spent cigarettes & associated ash deposits - also matches

Assistive Technology Program

A service that provides recommendations for technology that can help people with disabilities

Asynchronous communication A form of data transmission: info is sent & received, one character at a time, at irregular intervals. Start & stop bits 'tell' the receiving modem when data bits begin & end
ATM Asynchronous Transfer Mode - A high-speed connection-oriented protocol that packs digital information into 53-byte cells that can be switched quickly between logical connections on a network. The cells switch throughout a network over virtual circuit
Authentication The process that validates a user's login information on a network operating system or a multiuser system. Authentication usually involves resolving user names & passwords to an authorised user list
authoritative describes a DNS server hosting a zone, or a zone containing a name or record. When a DNS server is configured to host a zone, it is said to be authoritative for names that do exist or could exist within that zone. A DNS server is allowed to respond authoritatively to queries for domain names for which it is authoritative. A zone is said to be authoritative for a name if the name exists or could exist within a zone, and it is said to be authoritative for a record if the owner name of the record exists or could exist within a zone
authoritative restore In Backup, a type of restore operation performed on an Active Directory domain controller in which the objects in the restored directory are treated as authoritative, replacing (through replication) all existing copies of those objects. Authoritative restore is applicable only to replicated system state data such as Active Directory data and File Replication service data. Use the Ntdsutil.exe utility to perform an authoritative restore
Average Cell Rate Maximum sustainable or average rate (Cells/second) for sending cells to the network. Average Cell Rate specifies bandwidth utilization. This value must always be less than or equal to Peak Cell Rate
AXFR full zone transfer - The standard query type supported by all DNS servers to update and synchronize zone data when the zone has been changed. When a DNS query is made using AXFR as the specified query type, the entire zone is transferred as the response

B

B-channel aka bearer channel: single channel of ISDN that is used to carry either voice or data. ISDN Basic Rate Interface (BRI) has 2 B-channels. ISDN Primary Rate Interface (PRI) in North America has 23 B-channels. ISDN30e Primary Rate Interface (PRI) in Europe has 30 B-channels
B-ISDN

broadband integrated services digital network - An ITU-T communication standard for high-speed networking that provides new services, including voice, video, and data on the same network

Back plane A high-speed communications line to which individual components are connected.
Backbone The part of a network that serves as a communications highway for LAN-to-LAN traffic. LANs are connected to the backbone through bridges and routers.
Bandwidth Amount of data that can be transmitted over a given time period: The bandwidth determines the rate at which information can be transmitted over a computer channel, communications line, or bus. The greater the bandwidth, the greater number of megabits can be transmitted per second: An analog telephone line allows a bandwidth of 3,000 hertz (Hz), the difference between the lowest (300 Hz) and highest (3,300 Hz) frequencies it can carry. In digital communications, bandwidth is expressed in bits per second (bps)
Bandwidth on demand A cost-saving feature that allows a device to establish a communications link to the central LAN only when bandwidth is required to transfer data. Bandwidth on demand is suitable for high-speed connection of voice, data, and video services
BAP Bandwidth Allocation Protocol  - A PPP control protocol that is used on a multiprocessing connection to dynamically add and remove links
base priority - processor A precedence ranking that determines the order in which the threads of a process are scheduled for the processor. Use Task Manager to view and change base priorities
base priority - Message Queuing a property that specifies the queue's priority in a public queue. You can set the base priority from -32,768 to 32,767; the default priority is 0. Private queues do not support base priority. Message Queuing routes and delivers messages first by base priority, then by message priority
batch program aka batch files - An ASCII (unformatted text) file that contains one or more operating system commands. A batch program's file name has a .cmd or .bat extension. When you type the file name at the command prompt, or when the batch program is run from another program, its commands are processed sequentially
baud rate The speed at which a modem communicates. Baud rate refers to the number of times the condition of the line changes. This is equal to bits per second only if each signal corresponds to one bit of transmitted data. Modems must operate at the same baud rate in order to communicate with each other. If the baud rate of one modem is set higher than that of the other, the faster modem usually alters its baud rate to match that of the slower modem
BDC backup domain controller - In Windows NT Server 4.0 or earlier, a computer running Windows NT Server that receives a copy of the domain's directory database (which contains all account and security policy information for the domain). The copy is synchronized periodically and automatically with the master copy on the primary domain controller (PDC). BDCs also authenticate user logon information and can be promoted to function as PDCs as needed. Multiple BDCs can exist in a domain. Windows NT 3.51 and 4.0 BDCs can participate in a Windows 2000 domain when the domain is configured in mixed mode
BPDU Bridge Protocol Data Unit - Data messages exchanged across switches in an extended LAN with a spanning tree protocol topology. BPDU packets assure that data arrives at the intended destination. These packets contain information on addresses, costs, ports, and priorities. Network loop detection involves exchanging BPDU messages across bridges. Loop deletion entails placing redundant switch ports in a backup (blocked) state and shutting down selected bridge interfaces
BGP                      Border Gateway Protocol - A routing protocol that interconnects organisational networks and evaluates each of the possible routes to find the best one.
BIND Berkeley Internet Name Domain - An implementation of DNS written and ported to most available versions of the UNIX operating system. The Internet Software Consortium maintains the BIND software
BIND boot file Configuration file used by Domain Name System (DNS) servers running under versions of the Berkeley Internet Name Domain (BIND) software implementation. The BIND boot file is a text file, Named.boot, where individual lines in the file list boot directives used to start a service when the DNS server is started. By default, Microsoft DNS servers use DNS service parameters stored in the registry, but they allow the use of a BIND boot file as an alternative for reading boot configuration settings
bindery A database in Novell NetWare 3.x that contains organizational and security information about users and groups
BIOS basic input/output system - On x86-based computers, the set of essential software routines that test hardware at startup, start the operating system, and support the transfer of data among hardware devices. The BIOS is stored in read-only memory (ROM) so that it can be executed when a PC is powered up. Although critical to performance, the BIOS is usually invisible to users
Bit                     aka Binary Digit - The smallest unit of data that a computer processes. A bit is either ON or OFF, representing a 1 or a 0. A group of 8 bits makes up a byte, which can represent many types of information, such as a letter of the alphabet, a decimal digit, or other character
boot files The system files needed to start Windows. The boot files include Ntldr and Ntdetect.com
Boot Logging A process in which a computer that is starting (booting) creates a log file that records the loading of each device and service. The log file is called Ntbtlog.txt, and it is saved in the system root directory
boot partition The partition that contains the Windows operating system and its support files. The boot partition can be, but does not have to be, the same as the system partition
boot volume The volume that contains the Windows operating system and its support files. The boot volume can be, but does not have to be, the same as the system volume
BOOTP extensions A set of optional information types defined originally in RFC 1497 for use with BOOTP service and later supported by DHCP. In DHCP, these extensions form the legacy core set of client parameters available and supported by most standard DHCP and BOOTP servers
BOOTP bootstrap protocol - protocol used primarily on TCP/IP networks to configure diskless workstations. RFCs 951 and 1542 define this protocol. DHCP is a later boot configuration protocol that uses this protocol. The Microsoft DHCP service provides limited support for BOOTP service 
boot The process of starting or resetting a computer. When first turned on (cold boot) or reset (warm boot), the computer runs the software that loads and starts the computer's operating system, which prepares it for use
BPDU               Bridge Protocol Data Unit  - A data broadcast that informs each attached bridge of the configuration and operating state of every other attached bridge.
Bps                      Bits Per Second - The rate at which data is sent over a communication line [ie modem] during a data-transfer operation
Bridge A device that connects two LAN segments [or separate LANs] together at low protocol levels. These LAN segments may be of similar or dissimilar types, such as Ethernet and Token Ring. Inserting a bridge into a network segments the network. The bridge improves performance by keeping traffic contained within bridge segments by dividing the LAN into smaller units and keeping a list of service nodes on either side of it
Bridge Loop Path that links one network segment to another. The spanning tree protocol avoids bridge loops
Bridge Priority Determines which bridge is the root bridge
broadband

communications systems in which the medium of transmission (such as a wire or fiber-optic cable) carries multiple messages at a time, each message modulated on its own carrier frequency by a modem 

broadband connection

A high-speed connection. Broadband connections are typically 256 kilobytes per second (KBps) or faster. Broadband includes DSL and cable modem service

Broadcast A packet delivery system that transmits a copy of a given packet to all attached hosts. Broadcast is a special form of multicast in which the subset of machines to receive the packet consists of the entire set [ie destined for all hosts on a particular network segment]
buffer A region of RAM reserved for use with data that is temporarily held while waiting to be transferred between two locations, such as between an application's data area and an input/output device
built-in groups The default security groups installed with the operating system. Built-in groups have been granted useful collections of rights and built-in abilities. In most cases, built-in groups provide all the capabilities needed by a particular user. eg, if a domain user account belongs to the built-in Administrators group, logging on with that account gives a user administrative capabilities over the domain and the domain servers. To provide a needed set of capabilities to a user account, assign it to the appropriate built-in group
Burst Size (Cells) Maximum number of cells that the user can send at peak rate in a burst
bus A communication line used for data transfer among the components of a computer system. A bus essentially allows different parts of the system to share data. eg, a bus connects the disk-drive controller, memory, and input/output ports to the microprocessor
Byte aka Octet - Eight bits of information
bytes A unit of data that typically holds a single character, such as a letter, a digit, or a punctuation mark. Some single characters can take up more than one byte

C

Cable modem A device that enables a broadband connection to the www by using cable television infrastructure. maximum throughput of 10 megabits per second (Mbps)
cache For DNS and WINS, a local information store of resource records for recently resolved names of remote hosts. Typically, the cache is built dynamically as the computer queries and resolves names. It also helps optimize the time required to resolve queried names
cache file aka root hints file - A file used by the Domain Name System (DNS) server to preload its names cache when service is started. Also known as the root hints file because DNS uses resource records stored in this file to help locate root servers that provide referral to authoritative servers for remote names. For Windows DNS servers, the cache file is named Cache.dns and is located in the %SystemRoot%\System32\Dns folder
caching the temporay storing of recently used data values in a pool in memory for quicker access. For DNS, typically the ability of the DNS server to store information learned about the DNS namespace during the resolution of DNS queries. (eg, the DNS server can cache DNS records received from other DNS servers.) Caching is also available through the DNS Client service as a way for DNS clients to keep a cache of information learned during recent queries
caching resolver client-side DNS name resolution service that performs caching of recently learned DNS domain name information. The caching resolver service provides system-wide access to DNS-aware programs for resource records obtained from DNS servers during processing of name queries. Cached data is used for a limited period of time and aged according to the active Time-to-Live (TTL) value. You can set the TTL individually for each resource record (RR). Otherwise, it defaults to the minimum TTL set in the SOA RR for the zone
canonical name An object's distinguished name presented with the root first and without the LDAP attribute tags (such as: CN=, DC=). The segments of the name are delimited with forward slashes (/). eg CN=MyDocuments, OU=MyOU,DC=Microsoft,DC=Com is microsoft.com/MyOU/MyDocuments  
CAP Carrierless Amplitude and Phase Modulation - Modulation method used by modems and DSL equipment. Based on QAM. Signals modulate two wideband signals using passband modulation. CAP permits two to nine bits per frequency cycle
Carrier A company that provides communication circuits. Also, a signal that can be modulated or impressed with a second information-carrying signal. The carrier itself conveys no information until it is altered. Changes to the amplitude, frequency or phase modulation convey the information.
Carrier wave - Periodic waveform. A carrier may be modulated or unmodulated. It may also be continuous or switched. Typically, modems modulate the carrier wave with a data signal. Modulation represents the data signal by impressing a variation on some characteristic of the carrier wave. [ie a circuit may represent the signal as a proportional shift in carrier amplitude, frequency, or phase]. Demodulation (detection) eliminates the carrier wave and reproduces the signal. The carrier frequency must be significantly greater than the signal frequency. A modem may simultaneously apply more than one signal and more than one modulation method to the same carrier. The modulation method may suppress the carrier before transmission. In that case, the receiver must reinsert the carrier before demodulation can occur
cascading hubs A network configuration in which hubs are connected to other hubs
CBR Constant Bit Rate - an ATM service type that supports real-time applications with a fixed bandwidth. These applications, [eg a voice or video stream that require little or no cell loss and rigorous timing] produce data at regular intervals. The user can specify how much bandwidth to reserve
CCP Compression Control Protocol - A protocol used in the negotiation process in a PPP connection. CCP is one type of Network Control Protocol (NCP). NCPs are used to establish & configure different network protocol parameters for IP, IPX, and NetBEUI
CD            Carrier Detect - A signal sent from a modem to the PC to indicate that the modem is on-line
CD Compact Disc
CDMA Code Division Multiple Access
CD-R Recordable compact disc. Data can be burned to the CD but not erased
CD-RW Rewritable compact disc. Data can be copied to the CD on more than one occasion and can be erased [ie the disc is re-useable]
CDVT (Cells) - Parameter that constrains the number of cells that the user can send to the network at the maximum line rate
Central office The facility [ie the local exchange] owned by the ISDN service provider that contains the ISDN switching equipment needed to provide ISDN service to the customer premises. [also applies to analogue trunks]
certificate A digital document that is commonly used for authentication & secure exchange of information on open networks, such as the www, extranets & intranets. A certificate securely binds a public key to the entity that holds the corresponding private key. Certificates are digitally signed by the issuing certification authority and can be issued for a user, a computer, or a service. The most widely accepted format for certificates is defined by the ITU-T X.509 version 3 international standard 
CA certification authority - An entity responsible for establishing & vouching for the authenticity of public keys belonging to users (end entities) or other certification authorities. Activities of a certification authority can include binding public keys to distinguished names through signed certificates, managing certificate serial numbers, and certificate revocation
certification hierarchy A model of trust for certificates in which certification paths are created by means of the establishment of parent-child relationships between certification authorities
certification path An unbroken chain of trust, consisting of certificates from trusted certificate authorities, from a specific certificate to the root certification authority in a certification hierarchy
CF Card CompactFlash Card - memory storage device for palm-sized & handheld PCs, which don't have HDD
Channel A connecting path that carries information from a sending device to a receiving device. A channel can refer to a physical medium or to a specific frequency within a larger channel. eg A single ISDN2e Basic Rate Interface (BRI) connection has one physical connection but two channels for exchanging information between devices. This is called a bearer channel, implying a channel that carries information
child object An object that resides in another object. A child object implies relation. eg, a file is a child object that resides in a folder, which is the parent object
CHAP           Challenge Handshake Authentication Protocol - An authentication protocol in which the authenticator sends a challenge message to verify the identity of a remote user. CAHP is documented in RFC 1994, it uses the industry-standard Message Digest 5 (MD5) one-way encryption scheme to hash the response to a challenge issued by the remote access server.PPP calls must go through CHAP. Microsoft has created a Windows-specific variant of CHAP called MS-CHAP
Class A IP address A unicast IP address that ranges from 1.0.0.1 through 126.255.255.254. The first octet indicates the network, and the last three octets indicate the host on the network
Class B IP address A unicast IP address that ranges from 128.0.0.1 through 191.255.255.254. The first two octets indicate the network, and the last two octets indicate the host on the network
Class C IP address A unicast IP address that ranges from 192.0.0.1 to 223.255.255.254. The first three octets indicate the network, and the last octet indicates the host on the network. Network Load Balancing provides optional session support for Class C IP addresses (in addition to support for single IP addresses) to accommodate clients that make use of multiple proxy servers at the client site
Classfull addressing A state in which an IP address space is divided into three predefined categories - Class A (8-bit), Class B (16-bit), and Class C (24-bit)
Classless addressing A state in which an IP address space is divided into arbitrary sizes rather than the standard 8-bit, 16-bit, and 24-bit networks associated with classfull addressing.
client Any computer or program connecting to, or requesting the services of, another computer or program. Client can also refer to the software that enables the computer or program to establish the connection
client LAN or www - a computer that uses shared network resources provided by another computer (a server)
client request A service request from a client computer to a server computer or, for Network Load Balancing, a cluster of computers. Network Load Balancing forwards each client request to a specific host within the cluster according to the system administrator's load-balancing policy
Client/server A computer on a LAN that provides information or applications. The client-server splits the workload between desktop PCs (workstations) and one or larger computers (servers) connected on a LAN
CLIP classical IP over ATM - A proposed Internet standard, described in RFC 2225, that allows IP communication directly on the ATM layer, bypassing an additional protocol (such as Ethernet or Token Ring) in the protocol stack
CLIP Calling Line Identification Presentation - in telecomms, presentation of the callers CLI
ClipBook Server A system service that supports ClipBook Viewer, which allows pages to be seen by remote ClipBooks
Cluster aka allocation unit - The smallest amount of disk space that can be allocated to hold a file. All file systems used by Windows organize hard disks based on allocation units. The smaller the allocation unit size, the more efficiently a disk stores information. If you do not specify an allocation unit size when formatting the disk, Windows picks default sizes based on the size of the volume. These default sizes are selected to reduce the amount of space that is lost and the amount of fragmentation on the volume
cluster

computer networking: a group of independent computers that work together to provide a common set of services and present a single-system image to clients. The use of a cluster enhances the availability of the services and the scalability and manageability of the operating system that provides the services

cluster adapter The adapter that, when using multiple network adapters in each host of a Network Load Balancing cluster, handles the network traffic for cluster operations (the traffic for all hosts in the cluster). This adapter is programmed with the host's cluster IP address
Cluster Administrator An application that is used to configure a cluster and its nodes, groups, and resources. Cluster Administrator can run on any member of the trusted domain regardless of whether the computer is a cluster node
Cluster Administrator extension A software component that implements the Cluster Administrator extension application programming interface (API) for allowing Cluster Administrator to configure a new resource type
Cluster API A collection of functions that are implemented by the cluster software and used by a cluster-aware client or server application, a cluster management application, or a Resource DLL. The Cluster API is used to manage the cluster, cluster objects, and the cluster database
cluster disk A disk on a shared bus connected to the cluster nodes, which all the cluster nodes can access (though not at the same time)
Cluster service The essential software component that controls all aspects of server cluster operation and manages the cluster database. Each node in a server cluster runs one instance of the Cluster service
cluster-aware application An application that can run on a cluster node and that can be managed as a cluster resource. Cluster-aware applications use the Cluster API to receive status and notification information from the server cluster
cluster-unaware application An application that can run on a cluster node and be managed as a cluster resource but that does not support the Cluster API
Cluster.exe An alternative to using Cluster Administrator to administer clusters from the command prompt. You can also call Cluster.exe from command scripts to automate many cluster administration tasks
CMOS Complementary Metal Oxide Semiconductor: low power logic circuit: a specific type of semiconductor technology that requires very little power. The term has been popularized to mean a small storage area where the system keeps track of certain hardware parameters, such as HDD size, number of serial ports etc. aka Setup RAM.
CODEC Coder/Decoder - hardware that can convert audio or video signals between analog and digital forms (coder/decoder); hardware or software that can compress and uncompress audio or video data (compression/decompression); or the combination of coder/decoder and compression/decompression. Generally, a codec compresses uncompressed digital data so that the data uses less memory.
COM port The device name used to denote a serial communications port in DOS - a port that allows asynchronous communication of one byte at a time
community name A name used to group SNMP hosts. This name is placed in SNMP messages sent between SNMP-managed devices such as Windows 2000-based server computers and SNMP management stations. Typically, all hosts belong to Public, which is the standard name for a common community of all SNMP hosts
Compression A technique that reduces the number of bits needed to represent information in data transmission or storage. Compression also saves memory and bandwidth, and can increase the capacity of low-speed WAN links at minimal cost
Console Terminals used to monitor & control a PC or network. The console consists of an RS-232 compatible terminal port, together with compatible software for a VT100 (asynchronous) terminal
console tree The left pane in a Microsoft Management Console (MMC) that displays the items contained in the console. By default it is the left pane of a console window, but it can be hidden. The items in the console tree and their hierarchical organization determine the capabilities of a console
CNAME canonical resource record - A resource record used to map an alternate alias name to a primary canonical DNS domain name used in the zone
convergence The process of stabilizing a system after changes occur in the network. For routing, if a route becomes unavailable, routers send update messages throughout the internetwork, reestablishing information about preferred routes
convergence Network Load Balancing - a process by which hosts exchange messages to determine a new, consistent state of the cluster and to elect the host with the highest host priority, known as the default host. During convergence, a new load distribution is determined for hosts that share the handling of network traffic for specific TCP or UDP ports
count limit For Process Control, the maximum number of active processes in a process group. You can configure this in the Process Control snap-in
CRC              Cyclical Redundancy Check - An error-checking measure used to ensure the accuracy of transmitting data. The transmitted message is a small integer value computed from a sequence of octets. This value is used to detect errors that result when the sequence of octets is transmitted from one machine to another
CRC errors Errors caused by the failure of a cyclic redundancy check. A CRC error indicates that one or more characters in the data packet received were found garbled on arrival
CRL certificate revocation list - A document maintained & published by a certification authority that lists certificates that have been revoked
CRL distribution point An optional extension in an X.509v3 certificate that identifies how information is obtained. Also, a directory entry or other distribution source for certificate revocation lists
CryptoAPI An application programming interface (API) that is provided as part of Microsoft Windows. CryptoAPI provides a set of functions that allow applications to encrypt or digitally sign data in a flexible manner while providing protection for the user's sensitive private key data. Actual cryptographic operations are performed by independent modules known as cryptographic service providers (CSPs)
CSID called subscriber ID string - A string specifying the called subscriber ID transmitted by the receiving fax machine when receiving an inbound fax. This string is usually a combination of the fax or telephone number and the business name
CSMA/CD       Carrier Sense Multiple Access With Collision Detection - A method of getting onto and off of a LAN. Multiple workstations access a common transmission medium by listening until no signals are detected, then transmitting and checking to see if more than one signal is present. IEEE 802.3 and Ethernet LANs are based on the CSMA/CD standard transmission method
CSP cryptographic service provider - code that performs authentication, encoding & encryption services that Windows-based applications access through the CryptoAPI. A CSP is responsible for creating keys, destroying them, and using them to perform cryptographic operations. Each CSP provides a different implementation of the CryptoAPI. Some provide stronger cryptographic algorithms, while others contain hardware components, such as smart cards
CTL certificate trust list - A signed list of root certification authority certificates that an administrator considers reputable for designated purposes, such as client authentication or secure e-mail
CTS                  Clear To Send - A hardware signal defined by the RS232C standard that indicates that the transmission can proceed
Cycle One half of a periodic wave. ie a sinewave includes one positive and one negative cycle

D

D-channel aka data channel: separate channel of ISDN used for ISDN signaling. For ISDN Basic Rate Interface (BRI), the D-channel is 16 kilobits per second (Kbps). For ISDN Primary Rate Interface (PRI), the D-channel is 64 Kbps
DACL discretionary access control list - The part of an object's security descriptor that grants or denies specific users and groups permission to access the object. Only the owner of an object can change permissions granted or denied in a DACL
Data Compression The coding of data to save storage space or transmission time. Although data is already coded in digital form for computer processing, it can often be coded more efficiently (using fewer bits). There are many compression algorithms and utilities. Compressed data must be decompressed before it can be used
Data encryption A security procedure in which messages are enciphered in secret code so that only the intended receiver can read them.
datagram One packet, or unit, of information that includes relevant delivery information, such as the destination address, that is sent through a packet-switching network
data-overrun error A state in which the sending computer is transmitting characters faster than the receiving computer can accommodate them. If this problem persists, reduce the bps rate
data packet A unit of information transmitted as a whole from one device to another on a network
DCE                  Data Communications Equipment  - One of two types of hardware connected by an RS-232-C serial connection, the other being a Data Terminal Equipment (DTE) device. A DCE is an intermediary device that often transforms input from a DTE before sending it to a recipient. A modem, for example, is a DCE that modulates data from a microcomputer (DTE) and sends it along a telephone connection
DDE dynamic data exchange - A form of interprocess communication (IPC) implemented in the Microsoft Windows family of operating systems. Two or more programs that support dynamic data exchange (DDE) can exchange information and commands
DDR (memory) Double data Rate Synchronous - evolutionary technology derived from SDRAM
DLL dynamic-link library - operating system feature that allows executable routines (generally serving a specific function or set of functions) to be stored separately as files with .dll extensions. These routines are loaded only when needed by the program that calls them
dead-letter queue Message Queuing, a queue that stores nontransactional messages that are undeliverable or expired. These queues store failed messages on the computer on which the message expired. Messages in these queues are written to disk and are therefore recoverable
dedicated adapter The network adapter that, when using multiple network adapters in each host of a Network Load Balancing cluster, handles network traffic not related to cluster operations (the traffic for individual hosts on the network). This adapter is programmed with the host's dedicated IP address
dedicated circuit A telecommunications channel leased between 2 or more service points within one exchange or between different exchanges, usually at a monthly rate. aka Leased line  or a private line
default gateway the IP address of an IP router. the default gateway creates a default route in the IP routing table
default host The default host handles all the network traffic for TCP & UDP ports that are not covered by port rules
default network Macintosh -  the physical network on which the processes of a server reside as nodes and on which the server appears to users. The default network of the server must be one to which that server is attached. Only servers on AppleTalk Phase 2 internets have default networks
default zone The zone to which all Macintosh clients on the network are assigned by default
DEL Direct [analogue] exchange line
delegation For DNS, a name service record in the parent zone that lists the name server authoritative for the delegated zone
delegation The ability to assign responsibility for management and administration of a portion of the namespace to another user, group, or organization
denial-of-service attack An attack in which an attacker exploits a weakness or a design limitation of a network service to overload or halt the service, so that the service is not available for use. This type of attack is typically launched to prevent other users from using a network service such as a Web server or a file server
dependency A relationship of reliance between two resources that makes it necessary for them to run in the same group on the same node. eg, an application is dependent on the disks that contain its data resources
dependency tree A diagram for visualizing the dependency relationships between resources
dependent client Message Queuing - a computer that requires synchronous access to a Message Queuing server to perform all standard message queuing operations, such as sending and receiving messages and creating queues
DES                    Data Encryption Standard - A NIST-standard encryption technique that scrambles data into an unbreakable code for public transmission. DES uses a binary number as an encryption key with 72 quadrillion possible combinations
descendent key All the subkeys that appear when a key in the registry is expanded. A descendent key is the same as a subkey
desired zone The zone in which AppleTalk network integration appears on the network
destination document The document into which a package or a linked or embedded object is being inserted. For an embedded object, aka container document
device conflict A conflict that occurs when the same system resources have been allocated to two or more devices. System resources include interrupt request (IRQ) lines, direct memory access (DMA) channels, input/output (I/O) ports, and memory addresses
DFS Distributed File System
DFS link An element in the Distributed File System (DFS) namespace that lies below the root and maps to one or more targets, each of which corresponds to a shared folder or another DFS root
DFS root The starting point of the Distributed File System (DFS) namespace. The root is often used to refer to the namespace as a whole. A root maps to one or more root targets, each of which corresponds to a shared folder on a server
DFS topology The overall logical hierarchy of the Distributed File System (DFS), including elements such as roots, links, shared folders, and replica sets, as depicted in the DFS administrative console. This is not to be confused with the DFS namespace, which is the logical view of shared resources seen by users
DHCP              Dynamic Host Configuration Protocol - Protocol for automatic TCP/IP configurations [ie issues IP addresses for a user - a pc]. DHCP provides static and dynamic address allocation and management
  • A TCP/IP service protocol that offers dynamic leased configuration of host IP addresses and distributes other configuration parameters to eligible network clients. DHCP provides safe, reliable, and simple TCP/IP network configuration, prevents address conflicts, and helps conserve the use of client IP addresses on the network.
  • DHCP uses a client/server model where the DHCP server maintains centralized management of IP addresses that are used on the network. DHCP-supporting clients can then request and obtain lease of an IP address from a DHCP server as part of their network boot process
DHCP client A network-enabled device [eg PC] that can communicate with a DHCP server to obtain a dynamic leased IP configuration and related optional parameters
DHCP option Pre-defined address configuration parameters assigned to clients by a DHCP service. Parameters are  defined in Request for Comments (RFC) 1542
DHCP Relay

 

When a DHCP server is on a different LAN than the node broadcasting for DHCP service, the DHCP broadcast request must be forwarded across the router/WAN to a subnet where a DHCP server resides. To assure receipt of an IP address that corresponds to this subnet, the router must use a DHCP relay. The router needs to know the IP address of the DHCP server. With this address, the router can direct the request to the appropriate DHCP server
DHCP service resource A resource type that provides DHCP services from a cluster
DHCP server A computer running the Microsoft DHCP service that offers dynamic configuration of IP addresses and related information to DHCP-enabled clients.
DHCP/BOOTP Relay Agent The agent program or component responsible for relaying DHCP & BOOTP broadcast messages between a DHCP server and a client across an IP router. A DHCP relay agent supports DHCP/BOOTP message relay as defined in RFCs 1541 and 2131. The DHCP Relay Agent service is managed using the Routing and Remote Access service
dial-up connection The connection to a network or ISP using a device that uses the PSTN. This includes modems with a standard phone line, ISDN cards with high-speed ISDN lines, or X.25 networks
differential backup A backup that copies files created or changed since the last normal or incremental backup. It does not mark files as having been backed up (in other words, the archive attribute is not cleared). If you are performing a combination of normal and differential backups, restoring files and folders requires that you have the last normal as well as the last differential backup
differential data Saved copies of changed data that can be applied to an original volume to generate a volume shadow copy
direct cable connection A link between the I/O ports of two computers created with a single cable rather than a modem or other interfacing devices. In most cases, a direct cable connection is made with a null modem cable
Direct routing The transmission of a datagram from one machine directly to another
directory partition A contiguous subtree of the directory that forms a unit of replication. A given replica is always a replica of some directory partition. The directory always has at least three directory partitions: The schema, which defines the object classes and attributes contained in Active Directory. The configuration, which identifies the domain controllers, replication topology and other related information about the domain controllers within a specific implementation of Active Directory. One or more domains that contain the actual directory object data. A domain controller always stores the partitions for the schema, configuration, and its own (and no other) domain. The schema and configuration are replicated to every domain controller in the domain tree or forest. The domain is replicated only to domain controllers for that domain. A subset of the attributes for all domain objects is replicated to the global catalog
directory service Both the directory information source and the service that make the information available and usable. A directory service enables the user to find an object given any one of its attributes
distribution group A group that is used solely for e-mail distribution and that is not security-enabled. Distribution groups cannot be listed in discretionary access control lists (DACLs) used to define permissions on resources and objects. Distribution groups can be used only with e-mail applications (such as Microsoft Exchange) to send e-mail to collections of users. If you do not need a group for security purposes, create a distribution group instead of a security group
DLC Data Link Control - An address that uniquely identifies a node on a network. Every network adapter has a DLC address or DLC identifier (DLCI). Some network protocols, such as Ethernet and Token Ring, use DLC addresses exclusively. Other protocols, such as TCP/IP, use a logical address at the OSI Network layer to identify nodes. All network addresses must eventually be translated to DLC addresses. In TCP/IP networks, this translation is performed by the Address Resolution Protocol (ARP).
DLCI DLC identifier
DMA direct memory access - Memory access that does not involve the microprocessor. DMA is frequently used for data transfer directly between memory and a peripheral device such as a disk drive
DMT Discrete Multi Tone - the most common DSL modulation method. DMT creates 256 channels across the usable frequency spectrum. Each channel measures 4.3125KHz wide. Dividing the spectrum into channels allows DMT to function well in spite of nearby AM radio transmitters. The DMT modulator and demodulator is the FFT (Fast Fourier Transform) algorithm. Inside each channel, the modulation technique is QAM. Within each channel, the number of bits per symbol may be independently selected. Independent selection allows a DMT modem to be rate adaptive. Both G.DMT and G.Lite use DMT
DNS Domain Naming System - Mechanism used for translating Internet names of host computers into IP addresses [eg: www.sjgl.co.uk = 192.122.122.1]
  • A hierarchical, distributed database that contains mappings of DNS domain names to various types of data, such as IP addresses. DNS enables the location of computers and services by user-friendly names, and it also enables the discovery of other information stored in the database
DNS Relay DNS requests that the router forwards from a LAN node to a known DNS server. The router uses a DNS relay when the router functions as a NAPT device. The requests arrive at a DNS server over the WAN link. To function as a NAPT, the router requires DNS relay settings
DNS Server A service that maintains information about a portion of the Domain Name System (DNS) database and responds to and resolves DNS queries. A computer running this service is also known as a DNS server
DNS suffix For DNS, a character string that represents a domain name. The DNS suffix shows where a host is located relative to the DNS root, specifying a host?s location in the DNS hierarchy. Usually, DNS suffix describes the latter portion of a DNS name, following one or more of the first labels of a DNS name
Domain A description of a single computer, a whole department, or a complete site, used for naming and administrative purposes
domain A group of PCs that are part of a network and share a common directory database. A domain is administered as a unit with common rules and procedures. Each domain has a unique name.
  • An Active Directory domain is a collection of computers defined by the administrator of a Windows network. These computers share a common directory database, security policies, and security relationships with other domains. An Active Directory domain provides access to the centralized user accounts and group accounts maintained by the domain administrator. An Active Directory forest is made up of one or more domains, each of which can span more than one physical location.
  • A DNS domain is any tree or subtree within the DNS namespace. Although the names for DNS domains often correspond to Active Directory domains, DNS domains should not be confused with Active Directory domains
domain controller a Windows computer running Active Directory that manages user access to a network, which includes logging on, authentication, and access to the directory and shared resources
domain controller locator An algorithm that runs in the context of the Net Logon service and that finds domain controllers on a Windows 2000 network. Locator can find domain controllers by using DNS names (for IP/DNS-compatible computers) or by using NetBIOS names (for computers that are running Windows 3.x, Windows for Workgroups, Windows NT 3.5 or later, Windows 95, or Windows 98, or it can be used on a network where IP transport is not available)
domain DFS An implementation of DFS in which DFS topological information is stored in Active Directory. Because this information is made available on multiple domain controllers in the domain, domain DFS provides fault-tolerance for any distributed file system in the domain
domain local group A security or distribution group that can contain universal groups, global groups, and accounts from any domain in the domain tree or forest. A domain local group can also contain other domain local groups from its own domain. Rights and permissions can be assigned only at the domain containing the group
domain name The name given by an administrator to a collection of networked computers that share a common directory. Part of the Domain Name System (DNS) naming structure, domain names consist of a sequence of name labels separated by periods
domain namespace The database structure used by the Domain Name System (DNS)
domain naming master The domain controller assigned to control the addition or removal of domains in the forest. At any time, there can be only one domain naming master in the forest
domain of origin The parent DNS domain name that is used to root either a zone or a resource record within a zone. This name is joined to the end of unqualified or relative domain names to form a fully qualified domain name (FQDN) within the zone. In DNS Manager, the domain of origin will correspond to Zone name as it appears in the Add Zone Wizard or the name that appears in the Parent domain name field for any resource records created within the zone
domain tree In DNS, the inverted hierarchical tree structure that is used to index domain names. Domain trees are similar in purpose and concept to the directory trees used by computer filing systems for disk storage. eg when numerous files are stored on disk, directories can be used to organize the files into logical collections. When a domain tree has one or more branches, each branch can organize domain names used in the namespace into logical collections
domain tree In Active Directory, a hierarchical structure of one or more domains, connected by transitive, bidirectional trusts, that forms a contiguous namespace. Multiple domain trees may belong to the same forest
Dotted decimal notation A method of representing an IP address in which the 32-bit binary number is broken down into four groups of eight bits each. In turn, each byte is converted from binary to decimal numbers separated by dots
Dpi Dots per inch - measure of output device resolution and quality - ussually regarding printers
DRAM Dynamic Random Access Memory
DSA Digital Signature Algorithm
DSL Digital Subscriber Line - A type of high-speed Internet connection using standard telephone wires. aka broadband
DSLAM Digital Subscriber Line Access Multiplexer - Network device that receive signals from multiple customer DSL connections. DSLAM places signals on high speed lines with multiplexing techniques for the fastest phone line technology available
DSR                     Data Set Ready - A hardware signal defined by the RS-232C standrd to indicate that the device is ready to operate.
DSS Digital Signature Standard - A standard that uses the Digital Signature Algorithm (DSA) for its signature algorithm and SHA-1 as its message hash algorithm. DSA is a public-key cipher that is used only to generate digital signatures and cannot be used for data encryption
DTE                   Data Terminating Equipment
  • A communications device that is the source or destination of channels on a network. Terminals and computers are examples of DTE
  • In the RS-232-C hardware standard, any device, such as a remote access server or client, that has the ability to transmit information in digital form over a cable or a communications line
double-byte characters A set of characters in which each character is represented by two bytes. Some languages, such as Japanese, Chinese, and Korean, require double-byte character sets
drain Network Load Balancing, a command that disables new traffic handling for the rule whose port range contains the specified port. All ports specified by the port rule are affected
drainstop Network Load Balancing, a command that disables all new traffic handling on the specified hosts. The hosts then enter draining mode to complete existing connections. While draining, hosts remain in the cluster and stop their cluster operations when there are no more active connections. To terminate draining mode, explicitly stop cluster mode with the stop command, or restart new traffic handling with the start command. To drain connections from a specific port, use the drain command
drop folder Macintosh - a folder for which you have the Make Changes permission but not the See Files or See Folders permission. You can copy files into a drop folder, but you cannot see what files and subfolders the drop folder contains
DTMF                Dual Tone Multi Frequency -The formal names for push-button or touch-tone dialing. aka MF
DTR                     Data Terminal Ready A hardware signal defined by the RS-232C standard that is sent from a computer to a modem to indicate the computer is ready to receive a transmission.
dual boot A PC configuration that can start two different operating systems
duplex A system capable of transmitting information in both directions over a communications channel
DVD digital video disc - A type of optical disc storage technology that looks like a CD-ROM, but can store greater amounts of data. DVDs are often used to store movies and other multimedia content that requires large amounts of storage space
DVD decoder A hardware or software component that allows a digital video disc (DVD) drive to display movies on a pc
DVD drive A disk storage device that uses digital video disc (DVD) technology. A DVD drive reads both CD-ROM and DVDs; however, you must have a DVD decoder to display DVD movies on a pc
DWORD A data type composed of hexadecimal data with a maximum allotted space of 4 bytes
Dynamic address An Ethernet address that can be automatically deleted by the bridge if the bridge has not seen a packet from that address within a configuration time period (ageing). See static address
dynamic disk A physical disk that can be accessed only by Windows 2000 and Windows XP. Dynamic disks provide features that basic disks do not, such as support for volumes that span multiple disks. Dynamic disks use a hidden database to track information about dynamic volumes on the disk and other dynamic disks in the computer. You convert basic disks to dynamic by using the Disk Management snap-in or the DiskPart command line utility. When you convert a basic disk to dynamic, all existing basic volumes become dynamic volumes
dynamic storage A storage method in Windows that allows disk and volume management without requiring operating system restart
dynamic update An updated specification to the Domain Name System (DNS) standard that permits hosts that store name information in DNS to dynamically register and update their records in zones maintained by DNS servers that can accept and process dynamic update messages
dynamic volume A volume that resides on a dynamic disk. Windows supports five types of dynamic volumes: simple, spanned, striped, mirrored, and RAID-5. A dynamic volume is formatted by using a file system, such as FAT or NTFS, and it has a drive letter assigned to it

E

EAP Extensible Authentication Protocol - An extension to the Point-to-Point Protocol (PPP) that allows for arbitrary authentication mechanisms to be employed for the validation of a PPP connection
EDGE Enhanced Data through GSM Evolution (aka Evolved GSM or GSM 384)
EFI Extensible Firmware Interface - In computers with the Intel Itanium processor, the interface between a computer's firmware, hardware, and the operating system. The Extensible Firmware Interface (EFI) defines a new partition style called GUID partition table (GPT). EFI serves the same purpose for Itanium-based computers as the BIOS found in x86-based computers. However, it has expanded capabilities that provide a consistent way to start any compatible operating system and an easy way to add EFI drivers for new bootable devices without the need to update the computer's firmware
EFI system partition On Itanium-based computers, a portion on a GUID partition table (GPT) disk that is formatted with the FAT file system and contains the files necessary to start the computer. Every Itanium-based computer must have at least one GPT disk with an EFI system partition. The EFI system partition serves the same purpose as the system volume found on x86-based computers
EFS Encrypting File System - A feature in this version of Windows that enables users to encrypt files and folders on an NTFS volume disk to keep them safe from access by intruders
EGP                 Exterior Gateway Protocol - A network reachability protocol used mostly in TCP/IP environments.
EGSM Extended GSM
ELAN emulated local area network - A logical ATM network that emulates the services of an Ethernet or Token Ring LAN
EMI                  Electromagnetic Interference - The phenomenon that results when electromagnetic energy causes an unacceptable or undesirable response, malfunction, degradation, or interruption of the operation of electronic equipment.
EPS encapsulated PostScript file - A file that prints at the highest possible resolution for your printer. An EPS file may print faster than other graphical representations. Some Windows-based and non-Windows-based graphical programs can import EPS files
ESDI enhanced small device interface - A standard that can be used with high-capacity hard disks, floppy disk drives, and tape drives to allow these devices to communicate with a computer at high speeds
ESP Encapsulating Security Payload – ESP provides confidentiality. ESP can also provide integrity, authentication, anti-replay service, and limited traffic flow confidentiality. Options selected at the time of Security Association establishment determine provided services. For confidentiality, shared ESP supports shared key encryption algorithms, such as DES and Triple DES
Ethernet The most common type of connection of computers to a LAN. A local network design, characterised by 10 Mbps baseband transmission over a variety of cable media, and employing CSMA/CD as an access control mechanism
  • An IEEE 802.3 standard for contention networks. Ethernet uses a bus or star topology and relies on the form of access known as Carrier Sense Multiple Access with Collision Detection (CSMA/DC) to regulate communication line traffic. Network nodes are linked by coaxial cable, fiber-optic cable, or by twisted-pair wiring. Data is transmitted in variable-length frames containing delivery and control information and up to 1,500 bytes of data. The Ethernet standard provides for baseband transmission at 10 megabits (10 million bits) per second.
expanded memory Type of memory that can be added to IBM personal computers. The use of expanded memory is defined by the Expanded Memory Specification (EMS), which supports memory boards containing RAM that can be enabled or disabled by software
expansion slot A socket in a computer, designed to hold expansion boards and connect them to the system bus.
expire interval For DNS, the number of seconds that DNS servers operating as secondary masters for a zone will use to determine if zone data should be expired when the zone is not refreshed and renewed
 express message Message Queuing, a message that uses fewer resources and is faster than a recoverable message. However, because express messages are mapped to memory, they are lost if the computer storing them fails
extended memory Memory beyond one megabyte in 80286, 80386, 80486, and Pentium computers.
extended partition A type of partition that you can create only on basic master boot record (MBR) disks. Extended partitions are useful if you want to create more than four volumes on a basic MBR disk. Unlike primary partitions, you do not format an extended partition with a file system and then assign a drive letter to it. Instead, you create one or more logical drives within the extended partition. After you create a logical drive, you format it and assign it a drive letter. An MBR disk can have up to four primary partitions, or three primary partitions, one extended partition, and multiple logical drives 
external network number A 4-byte hexadecimal number used for addressing and routing purposes. The external network number is associated with physical network adapters and networks. To communicate with each other, all computers on the same network that use a specific frame type must have the same external network number. All external network numbers must be unique to the IPX internetwork
Extranet business to business Intranet allowing limited, controlled, secure access between a company's Intranet and designated, authenticated users from remote locations

F

failback The process of moving resources, either individually or in a group, back to their preferred node after the node has failed and come back online
failback policy Parameters that an administrator can set using Cluster Administrator that affect failback operations
failover The process of taking resource groups offline on one node and bringing them back online on another node. When a resource group goes offline, all resources belonging to that group go offline. The offline and online transitions occur in a predefined order, with resources that are dependent on other resources taken offline before and brought online after the resources upon which they depend
failover policy Parameters that an administrator can set, using Cluster Administrator, that affect failover operations
failover time The amount of time it takes a resource, either individually or in a group, to complete the failover process
Fair queuing A system in which the bridge sends messages of different lengths one character at a time to allow short messages to arrive at their destinations first.
Fast Ethernet A form of Ethernet that operates at 100 Mbps. Fast Ethernet uses CSMA/CD access method.
FAT file allocation table - A file system used by MS-DOS and other Windows-based operating systems to organize and manage files. The file allocation table (FAT) is a data structure that Windows creates when you format a volume by using the FAT or FAT32 file systems. Windows stores information about each file in the FAT so that it can retrieve the file later.
FAT32 A derivative of the file allocation table (FAT) file system. FAT32 supports smaller cluster sizes and larger volumes than FAT, which results in more efficient space allocation on FAT32 volumes
FCB file control block - A small block of memory temporarily assigned by a computer's operating system to hold information about a file that has been opened for use. An FCB typically contains such information as the file's identification, its location on disk, and a pointer that marks the user's current (or last) position in the file
FCS                  Frame Check Sequence - The special bits appended to the end of a data frame for error checking. An FCS calculation involves a polynomial equation being performed on the data and address fields. FCS is typically accurate to one packet in 4 billion.
FEP front-end processor - In communications, a computer that is located between communications lines and a main (host) computer and used to relieve the host of tasks related to communications; sometimes considered synonymous with communications controller. A front-end processor is dedicated entirely to handling transmitted information, including error detection and control; receipt, transmission, and possibly encoding of messages; and management of the lines running to and from other devices 
File and Print Servers for Macintosh A software component that allows Macintosh users access to a computer running any version of the Windows Server family. The services provided with this component allow personal computer and Macintosh users to share files and resources, such as printers on the AppleTalk network or printers attached to the Windows server
File server A computer hard disk or software configuration that lets users on a network share files and applications kept in storage.
File Server for Macintosh An AppleTalk network integration service that allows Macintosh clients and personal computer clients to share files. aka MacFile
File Share resource A file share accessible by a network path that is supported as a cluster resource by a Resource DLL
file system In an operating system, the overall structure in which files are named, stored, and organized. NTFS, FAT, and FAT32 are types of file systems
file type Windows -  a designation of the operational or structural characteristics of a file. The file type identifies the program, such as Microsoft Word, that is used to open the file. File types are associated with a file name extension. eg, files that have the .txt or .log extension are of the Text Document type and can be opened using any text editor
file type Macintosh -  a four-character sequence that identifies the type of a Macintosh file. The Macintosh Finder uses the file type and file creator to determine the appropriate desktop icon for that file
Filter Operating parameter used in LAN bridges & routers. When set, the filter causes bridges and routers to block transfer of packets between LANs
filter Indexing Service - software that extracts content and property values from a document in order to index them
filter IPSec - a specification of IP traffic that provides the ability to trigger security negotiations for a communication based on the source, destination, and type of IP traffic
Filtering The process used to ensure that only selected frames are forwarded
filtering mode Network Load Balancing - the method by which network traffic inbound to a cluster is handled by the hosts within the cluster. Traffic can either be handled by a single server, load balanced among the hosts within the cluster, or disabled completely
Filtering rate The number of packets that the bridge can inspect per second
FIPS 140-1 Federal Information Processing Standard 140-1 - A standard entitled Security Requirements for Cryptographic Modules. FIPS 140-1 describes government requirements that hardware and software cryptomodules should meet for Sensitive but Unclassified (SBU) use
firewall A combination of hardware and software that provides a security system, usually to prevent unauthorized access from outside to an internal network or intranet. A firewall prevents direct communication between network and external computers by routing communication through a proxy server outside of the network. The proxy server determines whether it is safe to let a file pass through to the network. aka a security-edge gateway
Firmware Any software stored in a form of read-only memory that maintains its contents when power is removed
Flooding A packet-switched network routing method by which identical packets are sent in all directions to ensure they search their intended destination.
Flow control management of transmission between two devices. Flow control controls the timing of signals. It enables communication between slower-speed devices and higher-speed devices by ensuring the receiving station is able to accept the next block of data before the sending station sends it
FM Frequency Modulation - Modulation method used by modems, radio, and DSL equipment. The signal modulates or alters the frequency or pitch of the carrier. In regular FM, the carrier is a sinewave. The frequency of the modulated carrier changes in proportion to signal amplitude. FM creates an infinite number of sidebands. These sidebands contain the signal data. With an equivalent signal, FM tends to require more bandwidth than AM does. FM's advantage is that it’s less subject to impulse noise and static than AM
foreign computer A computer that uses another message queuing system but, through a connector application, can exchange messages with computers that run Message Queuing
forest A collection of one or more Windows domains that share a common schema, configuration, and global catalog and are linked with two-way transitive trusts
FORTEZZA A family of security products, including PCMCIA-based cards, compatible serial port devices, combination cards (such as FORTEZZA/Modem and FORTEZZA/Ethernet), server boards, and others. FORTEZZA is a registered trademark held by the National Security Agency
Forwarding The process that sends frames over a link.
Forwarding rate The number of packets per second that can move across the bridge
Forward Delay Time Timeout value employed by all bridges in the bridged LAN. The root sets the forward delay value.
FQDN fully qualified domain name - A DNS domain name that has been stated unambiguously so as to indicate with absolute certainty its location in the domain namespace tree. Fully qualified domain names differ from relative names in that they are typically stated with a trailing period (.) - eg, host.example.microsoft.com. - to qualify their position to the root of the namespace
Frame A fixed block of data bits with a flag at each end to indicate the beginning and end of the frame. The defined format enables network equipment to recognise the meaning and purpose of specific bits. aka a packet, in LAN terminology
frame type The way in which a network type, such as Ethernet, formats data to be sent over a network. When multiple frame types are allowed for a particular network type, the packets are structured differently and are, therefore, incompatible. All computers on a network must use the same frame type to communicate. aka frame format
free media pool A logical collection of unused data-storage media that can be used by applications or other media pools. When media are no longer needed by an application, they are returned to a free media pool so that they can be used again
FTP File Transfer Protocol - A TCP/IP protocol in LAN technology that is used to log on to the network, list directories, and copy files. FTP can also perform ASCII to EBCIDIC conversions. Both computers must support their respective FTP roles: one must be an FTP client and the other an FTP server.
Full duplex A communications channel through which data can travel in both directions at once. See half duplex.
full zone transfer (AXFR) The standard query type supported by all DNS servers to update and synchronize zone data when the zone has been changed. When a DNS query is made using AXFR as the specified query type, the entire zone is transferred as the response

G

Gateway The entrance & exit to a communications network. In networks: a port that connects multiple networks or subnetworks. Incoming and outgoing signals from and to dissimilar networks are converted from one form to another in terms of speed, protocols, and interchange codes
gateway Novell NetWare networks: a gateway acts as a bridge between the server message block (SMB) protocol used by Windows networks and the NetWare core protocol (NCP) used by NetWare networks. aka an IP router
G.992.2 The standard applicable to the installation of ADSL over a DEL bearer [aka G.Lite]
GDI Graphics Device Interface
GDI objects Objects from the Graphics Device Interface (GDI) library of application programming interfaces (APIs) for graphics output devices. In Task Manager, the number of GDI objects currently used by a process
G.DMT he ADSL standard approved by the ITU. G.DMT indicates full-rate ADSL, which provides standards for higher speed ADSL than G.Lite. G.DMT provides maximum data rates of 8 Mbps downstream from the subscriber and 1.5 Mbps upstream from the subscriber
Generic Service resource A Windows service that is supported as a cluster resource by a Resource DLL
gigabyte (GB) 1,024 megabytes, though often interpreted as approximately one billion bytes
G.lite Standard way to install ADSL service. Over regular phone lines, G.Lite makes possible Internet connections to computers at up to 1.5 Mbps. Officially known as G.992.2.
global account In an Active Directory network, a normal user account in a user's domain. Most user accounts are global accounts. If there are multiple domains in the network, it is best if each user in the network has only one user account in only one domain, and each user's access to other domains is accomplished through the establishment of domain trust relationships
global catalog A domain controller that contains a partial replica of every domain in Active Directory. In other words, a global catalog holds a replica of every object in Active Directory, but with a limited number of each object's attributes. The global catalog stores those attributes most frequently used in search operations (such as a user's first and last names) and those attributes required to locate a full replica of the object.

The Active Directory replication system builds the global catalog automatically. The attributes replicated into the global catalog include a base set defined by Microsoft. Administrators can specify additional properties to meet the needs of their installation

global group A security or distribution group that can have users, groups, and computers from its own domain as members. Global security groups can be granted rights and permissions on resources in any domain in the forest. Global groups cannot be created or maintained on computers running Windows XP Professional. However, for Windows XP Professional computers that participate in a domain, domain global groups can be granted rights and permissions at those workstations and can become members of local groups at those workstations
glue chasing The follow-up queries or successive lookups that are made to resolve glue records in a zone to other remote DNS servers that are authoritative for a derivative zone. When glue chasing is performed, name server (NS) resource records for delegated DNS servers are chased, or followed, by using successive queries to resolve the servers named in NS records to their host address (A) resource records and to obtain server IP addresses
glue record A resource record for out-of-zone information used to provide helpful pointer information for locating DNS servers that have been delegated authority for specific subdomains derived from a zone's domain of origin. These records are used to glue zones together and provide an effective delegation and referral path for other DNS servers to follow when performing a recursive lookup to fully resolve a name
GPRS An Extension to the GSM standard to include packet data services
GPS Global Positioning System
GPT GUID partition table - A disk-partitioning scheme that is used by the Extensible Firmware Interface (EFI) in Itanium-based computers. GPT offers more advantages than master boot record (MBR) partitioning because it allows up to 128 partitions per disk, provides support for volumes up to 18 exabytes in size, allows primary and backup partition tables for redundancy, and supports unique disk and partition IDs (GUIDs)
group A collection of users, computers, contacts, and other groups. Groups can be used as security or as e-mail distribution collections. Distribution groups are used only for e-mail. Security groups are used both to grant access to resources and as e-mail distribution lists
group account A collection of user accounts. By making a user account a member of a group, you give the related user all the rights and permissions granted to the group
group memberships The groups to which a user account belongs. Permissions and rights granted to a group are also provided to its members. In most cases, the actions a user can perform in Windows are determined by the group memberships of the user account to which the user is logged on
group name A unique name identifying a local group or a global group to Windows. A group's name cannot be identical to any other group name or user name in its own domain or computer
Group Policy The Microsoft Management Console (MMC) snap-in that is used to edit Group Policy objects
Group Policy object A collection of Group Policy settings. Group Policy objects are essentially the documents created by the Group Policy snap-in, a Windows utility. Group Policy objects are stored at the domain level, and they affect users and computers contained in sites, domains, and organizational units. In addition, each Windows computer has exactly one group of settings stored locally, called the local Group Policy object
GSM Groupe Special Mobile or Global Systems for Mobile Communications: the world standard for digital cellular networks that originated in Europe - operates at 900MHz, 1800MHz & 1900MHz
guest account  built-in account used to log on to a computer running Windows when a user does not have an account on the computer or domain, or in any of the domains trusted by the computer's domain

H

Half duplex The transmission of data in both directions, but only in one direction at a time
handle In the user interface, an interface added to an object that facilitates moving, sizing, reshaping, or other functions pertaining to an object. In programming, a pointer to a pointer, that is, a token that lets a program access an identified resource
handle count In Task Manager, the number of object handles in a process's object table
handshaking A series of signals acknowledging that communication can take place between computers or other devices. A hardware handshake is an exchange of signals over specific wires (other than the data wires), in which each device indicates its readiness to send or receive data. A software handshake consists of signals transmitted over the same wires used to transfer data, as in modem-to-modem communications over telephone lines
hardware compression A feature available on some tape devices that automatically compresses the data that is being stored on the device. This is usually an option that is turned on or off in a backup program
hardware configuration Resource settings that have been allocated for a specific device. Each device on your computer has a hardware configuration, which may consist of IRQ lines, DMA, an I/O port, or memory address settings
hardware decoder A type of digital video disc (DVD) decoder that allows a DVD drive to display movies on a computer screen. A hardware decoder uses both software and hardware to display movies
hardware profile Data that describes the configuration and characteristics of specific computer equipment. This information can be used to configure computers for using peripheral devices
hardware type A classification for similar devices. eg, Imaging Device is a hardware type for digital cameras & scanners
hash A fixed-size result that is obtained by applying a one-way mathematical function (sometimes called a hash algorithm) to an arbitrary amount of data. If there is a change in the input data, the hash changes. The hash can be used in many operations, including authentication and digital signing. aka message digest 
hash algorithm An algorithm used to produce a hash value of some piece of data, such as a message or session key. A good hash algorithm has a quality where changes in the input data can change every bit in the resulting hash value; for this reason, hashes are useful in detecting any modification in a large data object, such as a message. Furthermore, a good hash algorithm makes it computationally infeasible to construct two independent inputs that have the same hash. Typical hash algorithms include MD2, MD4, MD5, and SHA-1. aka a hash function
HDD Hard Disk Drive - a HDD contains one or more inflexible platters coated with material in which data can be recorded magnetically with read/write heads. The hard disk exists in a sealed case that protects it and allows the head to fly 10 millionths to 25 millionths of an inch above the surface of a platter
HDLC               High-Level Data Link Control - An ISO communications protocol used in X.25 packet-switching networks. HDLC provides error correction at the DCE
Hello Time Time interval between generations of configuration BPDUs. The root bridge generates configuration BPDUs
hexadecimal A base-16 number system represented by the digits 0 through 9 and the uppercase or lowercase letters A (equivalent to decimal 10) through F (equivalent to decimal 15)
histogram A chart consisting of horizontal or vertical bars, the widths or heights of which represent the values of certain data
hive A section of the registry that appears as a file on the HDD. The registry subtree is divided into hives (named for their resemblance to the cellular structure of a beehive). A hive is a discrete body of keys, subkeys, and values that is rooted at the top of the registry hierarchy. A hive is backed by a single file and a .log file, which are in the systemroot\System32\Config or the systemroot\Profiles\username folders.

By default, most hive files (Default, SAM, Security, and System) are stored in the systemroot\System32\Config folder. The systemroot\Profiles folder contains the user profile for each user of the computer. Because a hive is a file, it can be moved from one system to another. However, you must use the Registry Editor to edit the file

HMAC Hash-based Message Authentication Mode - A mechanism for message authentication using cryptographic hash functions. HMAC can be used with any iterative cryptographic hash function (eg, MD5 and SHA-1) in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying hash function
home folder A folder (usually on a file server) that administrators can assign to individual users or groups. Administrators use home folders to consolidate user files onto specific file servers for easy backup. Home folders are used by some programs as the default folder for the Open and Save As dialog boxes. aka home directories
Host Any computer connected to the network that serve as a source or is the recipient of information: The  computer runs a server program or service used by network or remote clients. For Network Load Balancing, a cluster consists of multiple hosts connected over a LAN
host name The DNS name of a device on a network. These names are used to locate computers on the network. To find another computer, its host name must either appear in the Hosts file or be known by a DNS server. For most Windows computers, the host name and the computer name are the same
host priority

For Network Load Balancing, a host's precedence for handling default network traffic for TCP and UDP ports. It is used if a host within the cluster goes offline, and it determines which host within the cluster will assume responsibility for the traffic previously handled by the offline host

Hosts file

A local text file in the same format as the 4.3 Berkeley Software Distribution (BSD) UNIX /etc/hosts file. This file maps host names to IP addresses
HSCSD High Speed Circuit Switched Data is a GSM enhancement that allows several channels combined for data transmission - by combining two channels, it can increase the throughput to 19299 bits/second
HTML Hypertext Markup Language - A simple markup language used to create hypertext documents that are portable from one platform to another. HTML files are simple ASCII text files with codes embedded (indicated by markup tags) to denote formatting and hypertext links
HTTP Hypertext Transfer Protocol - The protocol used to transfer information on the www. An HTTP address (one kind of Uniform Resource Locator [URL]) takes the form: http://www.microsoft.com
Hub A LAN device that receives data from one link and rebroadcasts it to other links.
  • A common connection point for devices in a network. Typically used to connect segments of a local area network (LAN), a hub contains multiple ports. When data arrives at one port, it is copied to the other ports so that all segments of the LAN can see the data.
hubbed mode A mode in which the ARP/MARS provides ATM addresses to requesting clients in the form of a multicast server (MCS) list value. In this mode, the ARP/MARS acts as a multicast server, providing active forwarding of all multicast and broadcast traffic destined for IP addresses contained within the ranges specified in the list
hyperlink Often colored & underlined text or a graphic that you click to go to a file, a location in a file, an HTML page on the World Wide Web, or an HTML page on an intranet

I

IAP Internet Access Provider
ICMP             Internet Control Message Protocol - A TCP/IP protocol that generates error messages, control messages, test packets, and information messages related to IP. [eg a router uses ICMP to notify the sender that the router’s destination node is unavailable. A ping utility sends ICMP echo requests to verify the an IP address]
ICT Information and Communication Technology
IDE integrated device electronics - A type of disk-drive interface in which the controller electronics reside on the drive itself, eliminating the need for a separate adapter card. IDE offers advantages such as look-ahead caching to increase overall performance
IEEE            Institute of Electrical and Electronics Engineers - A professional society whose purpose includes the promotion of standardisation in the fields of electrical, electronics, and computer engineering, and computer science
IEEE 1394 A standard for high-speed serial devices such as digital video & audio editing equipment
IEEE 1394 connector A type of connector that enables connection of high-speed serial devices.

If a device is IEEE 1394 compatible, you can connect the device to the IEEE 1394 connector while the computer is running and Windows will detect the device and inform you when it is ready for use. Similarly, you can unplug the device while the computer is running, but you should use the Add Hardware Wizard to inform Windows that you are unplugging the device. Windows will then inform you when the device can be unplugged from the computer.

The IEEE 1394 bus is used primarily to connect high-end digital video and digital audio devices to your computer; however, some hard disks, printers, scanners, and DVD drives can also be connected to your computer using the IEEE 1394 connector

IETF Internet Engineering Task Force - An open community of network designers, operators, vendors, & researchers concerned with the evolution of Internet architecture and the smooth operation of the Internet. Technical work is performed by working groups organized by topic areas (such as routing, transport, and security) and through mailing lists. Internet standards are developed in IETF Requests for Comments (RFCs), which are a series of notes that discuss many aspects of computing and computer communication, focusing on networking protocols, programs, & concepts
IGMP Internet Group Management Protocol - A protocol used by IP hosts to report their multicast group memberships to any immediately neighboring multicast routers
IIS Internet Information Services - Software services that support Web site creation, configuration, and management, along with other Internet functions. Internet Information Services include Network News Transfer Protocol (NNTP), File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP)
IIS Server Instance resource A server-instance designation used with Internet Information Services (IIS) that supports the WWW and FTP services. IIS server instances are supported as cluster resources by a Resource DLL. IIS Server Instance resources may have dependencies on IP Address resources, Network Name resources, and Physical Disk resources. Access information for server instances does not fail over
IMEs Input Method Editors - text service -  program that enables a user to enter or edit text. Used to enter East Asian language characters with a keyboard
import media pool A logical collection of data-storage media that has not been cataloged by Removable Storage. Media in an import media pool should be cataloged as soon as possible so that they can be used by an application
in-addr.arpa domain A special top-level DNS domain reserved for reverse mapping of IP addresses to DNS host names
incremental backup A backup that copies only those files created or changed since the last normal or incremental backup. It marks files as having been backed up (in other words, the archive attribute is cleared). If you use a combination of normal and incremental backups to restore data, you will need to have the last normal backup and all incremental backup sets
independent client A computer with Message Queuing installed that can host queues and store messages locally. Independent clients do not require synchronous access to a Message Queuing server to send and receive messages, but they can use Message Queuing servers with routing enabled for efficient message routing
.inf file name extension: files that contain device info or scripts that control hardware operations
infrared file transfer Wireless file transfer between a computer and another computer or device using infrared light
infrared network connection A direct or incoming network connection to a remote access server using an infrared port
infrared port An optical port on a device [eg PC] that enables communication with other devices via infrared light
infrastructure master The domain controller assigned to update group-to-user references whenever group memberships are changed, and to replicate these changes to any other domain controllers in the domain. At any time, there can be only one infrastructure master in a particular domain
interactive dialog box A dialog box that requires a response from the user. Intermediary devices such as a security host require such a dialog box as an added layer of security between the client and the remote access server. In such dialog boxes, the user types an access code or a user name and password on the remote access terminal screen
interactive logon A network logon from a computer keyboard, when the user types information in the Logon Information dialog box displayed by the computer's operating system
inheritance A mechanism that allows a given access control entry (ACE) to be copied from the container where it was applied to all children of the container. Inheritance can be combined with delegation to grant administrative rights to a whole subtree of the directory in a single update operation
Initial master A shared folder whose existing files and folders are replicated to other shared folders when replication is initially configured. After replication is complete, there is no initial master, since any of the replicas can accept changes and propagate them to the other replicas. The initial master then becomes another replica
intranet A network within an organization that uses Internet technologies and protocols, but is available only to certain people, such as employees of a company - access must be authorised and is protected by a firewall. aka private network
interconnect A private network that connects nodes in a cluster
Interconnectivity gateway A gateway that ensures connectivity across attached networks of different natures without ensuring compatibility between Applications
Interface Name Router interface that will be configured
internal network number A 4-byte hexadecimal number used for addressing and routing purposes. The internal network number identifies a virtual network inside a computer. The internal network number must be unique to the IPX internetwork. aka virtual network number
international prefix Digits dialed before the country code to access the international phone service. The actual digits depend on the country or region in which you are dialing an international number. eg, in the UK, the prefix for international dialing is 00. Signified in a dial string by a + [eg + 44 1926 817594]
Internet A computer network that joins together many government, military, commercial, university, and private computers over telephone lines & private circuits
Internet address

 

Aka Uniform Resource Locator (URL). - An address for a resource on the Internet that is used by Web browsers to locate Internet resources. An Internet address typically starts with a protocol name, followed by the name of the organization that maintains the site; the suffix identifies the kind of organization it is. eg, the address http://www.sjgl.co.uk/ provides the following information:

http: Web server uses the Hypertext Transfer Protocol.

www: site is on the World Wide Web.

.co.uk: This is a UK based company

Internet Protocol multicasting The extension of local area network multicasting technology to a TCP/IP network. Hosts send and receive multicast datagrams, the destination fields of which specify IP host group addresses rather than individual IP addresses. A host indicates that it is a member of a group by means of the Internet Group Management Protocol (IGMP)
intermediary device A device other than a modem or X.25 PAD, located between a network connection and the remote access server. This device is typically a modem-pool switch or security host and requires either a static or interactive dialog box between the client and itself
Interoperability gateways A gateway that provides application protocol translation, transport & routing across attached networks
interrupt A request for attention from the processor. When the processor receives an interrupt, it suspends its current operations, saves the status of its work, and transfers control to a special routine known as an interrupt handler, which contains the instructions for dealing with the particular situation that caused the interrupt
I/O port input/output port - A channel through which data is transferred between a device and the microprocessor. The port appears to the microprocessor as one or more memory addresses that it can use to send or receive data
IP                  Internetworking Protocol / Internet Protocol- The protocol that allows a packet of information to travel through networks and LANs: The network layer protocol from the TCP/IP suite of protocols. A standard describing software that keeps track of the internetwork address for different nodes, routes outgoing messages, and recognises incoming messages
IP address A unique 32-bit address that identifies LAN devices on a TCP/IP network or the Internet. An IP address consists of four groups of digits; each group has a maximum value of 255 (for example, 205.115.47.5) and contains a network (subnet) portion and a host portion. This partition makes routing efficient

When a router port detects a packet, the router checks the routing table. The port attempts to match the network number of the destination IP address with its routing table entry. If the port finds a match, it forwards the packet to the destination network. With no match, the port forwards the packet to a router defined as the default gateway [ie the www]

  • A 32-bit address used to identify a node on an IP internetwork. Each node on the IP internetwork must be assigned a unique IP address, which is made up of the network ID, plus a unique host ID. This address is typically represented with the decimal value of each octet separated by a period (eg, 192.168.7.27). In this version of Windows, you can configure the IP address statically or dynamically through DHCP
IP Address resource a  32-bit number in dotted decimal format that represents an Internet Protocol (IP) address and is supported as a cluster resource by a Resource DLL provided with Windows
IP routing The action of directing network traffic according to the rules of the TCP/IP protocol.
IP subnetworking and masking A mask is a value associated with each IP address. A mask is configured by the network manager and allows the nodes and routers to read the portion of the IP address that represents the network (subnetwork) number
IPSec Internet Protocol security - A set of industry-standard, cryptography-based protection services and protocols. IPSec protects all protocols in the TCP/IP protocol suite and Internet communications using L2TP
IPX Internetwork Packet Exchange - A network protocol native to Novell NetWare that controls addressing and routing of packets within and between LANs. IPX does not guarantee that a message will be complete (no lost packets)
IPX/SPX Transport protocols used in Novell NetWare networks, which together correspond to the combination of TCP and IP in the TCP/IP protocol suite. Windows implements IPX through NWLink
IR infrared
IrDA Infrared Data Association - industry organization of computer, component & telecommunications vendors who maintain the standards for infrared communication between computers and peripheral devices
IRQ lines interrupt request lines - Hardware lines over which devices can send signals to get the attention of the processor when the device is ready to accept or send information. Each device must have a unique IRQ line
ISA Industry Standard Architecture
ISA expansion slot A connection socket for a peripheral designed to the Industry Standard Architecture (ISA) on a computer motherboard
ISDN Integrated Services Digital Network - international telecommunications standard that enables a communications channel to carry digital data simultaneously with voice & video information. eg ISDN2e can achieve 128 Kbps. go to isdn
ISM intersite messaging service - A service that supports transports for asynchronous, site-to-site messaging. Each transport serves two major roles: send/receive and topology queries (such as, what are the various sites connected by this transport, and at what cost?). The intersite messaging services shipped in Windows are RPC and SMTP (mail)
ISO International Standards Organisation - A voluntary, non-treaty organisation founded in 1946,  responsible for creating international standards in areas including computers & communications
ISP Internet Service Provider [eg Demon]: A company that provides access to the www. An ISP provides a telephone number, a user name, a password, and other connection information so users can connect their computers to the ISP's computers. An ISP typically charges a monthly or hourly connection fee
Itanium An Intel microprocessor that uses explicitly parallel instruction set computing and 64-bit memory addressing
ITU International Telecommunication Union
ITU-T International Telecommunication Union-Telecommunication Sector - The organisation that has replaced the CCITT as the world's leading telecommunications standards organisation
IXFR incremental zone transfer - An alternate query type that can be used by some DNS servers to update and synchronize zone data when a zone is changed. When incremental zone transfer is supported between DNS servers, servers can keep track of and transfer only those incremental resource record changes between each version of the zone

J

Jumper A wire that connects two pins together to form a closed circuit. Jumpers are most often used to test and configure printed circuit board assemblies.
Jumper Comms: A wire that connects a circuit to a device
junction point

A physical location on a hard disk that points to data located at another location on the hard disk or another storage device. Junction points are created when you create a mounted drive. You can also create a junction point using the linkd command

K

kbps                 Kilabits Per Second - A thousand bits per second
KDC Key Distribution Center - A network service that supplies session tickets and temporary session keys used in the Kerberos V5 authentication protocol. In Windows 2000 and Windows XP, the KDC runs as a privileged process on all domain controllers
Kerberos V5 authentication protocol An authentication mechanism used to verify user or host identity. The Kerberos V5 authentication protocol is the default authentication service for Windows 2000. Internet Protocol security (IPSec) and the QoS Admission Control Service use the Kerberos protocol for authentication
kernel The core of layered architecture that manages the most basic operations of the operating system and the computer's processor. The kernel schedules different blocks of executing code, called threads, for the processor to keep it as busy as possible and coordinates multiple processors to optimize performance. The kernel also synchronizes activities among Executive-level subcomponents, such as I/O Manager and Process Manager, and handles hardware exceptions and other hardware-dependent functions. The kernel works closely with the hardware abstraction layer
key Registry Editor: a folder that appears in the left pane of the Registry Editor window. A key can contain subkeys and value entries. eg, Environment is a key of HKEY_CURRENT_USER
key IP security (IPSec): a value used in combination with an algorithm to encrypt or decrypt data. Key settings for IP security are configurable to provide greater security

L

L2TP Layer 2 Tunneling Protocol - industry-standard Internet tunneling protocol. Unlike Point-to-Point Tunneling Protocol (PPTP), L2TP does not require IP connectivity between the client workstation and the server. L2TP requires only that the tunnel medium provide packet-oriented point-to-point connectivity. The protocol can be used over media such as ATM, Frame Relay, and X.25. L2TP provides the same functionality as PPTP. Based on Layer 2 Forwarding (L2F) and PPTP specifications, L2TP allows clients to set up tunnels across intervening networks.
label

ech part of a full DNS domain name that represents a node in the domain namespace tree. Domain names are made up of a sequence of labels, such as the three labels (example, microsoft, and com) that make up the DNS domain name example.microsoft.com. Each label used in a DNS name must be 63 bytes or less in character length

LAN Local Area Network - A short-distance (usually within a single building) data communications network used to link together a group of computers, printers, and other devices
LANE LAN emulation - A set of protocols that allow existing Ethernet & Token Ring LAN services to overlie an ATM network. LANE allows connectivity among LAN- and ATM-attached stations
LANE configuration server a service that assigns individual LANE clients to particular ELANs by directing them to the LES
latency

aka propagation delay: In Active Directory replication, the delay between the time an update is applied to a given replica and the time it is applied to some other replica

Leased line A telecommunications channel leased between 2 or more service points within one exchange or between different exchanges, usually at a monthly rate. aka dedicated circuit or a private line
LCP Link Control Protocol - A PPP control protocol that negotiates link and PPP parameters to dynamically configure the data-link layer of a PPP connection [provides a method of establishing, configuring, maintaining, and terminating a point-to-point connection]
LCR Least Cost Routing - process in telecomms for the choosing of call route based on cost
LDAP Lightweight Directory Access Protocol - The primary access protocol for Active Directory. Lightweight Directory Access Protocol (LDAP) version 3 is defined by a set of Proposed Standard documents in Internet Engineering Task Force (IETF) RFC 2251
LDIF

LDAP Data Interchange Format - Files that contain LDAP instructions that manipulate directory information. Before the LDAP commands in an LDIF file are carried out, they can be read or modified

lease The length of time for which a DHCP client can use a dynamically assigned IP address configuration. Before the lease time expires, the client must either renew or obtain a new lease with DHCP
LEC LAN emulation client - The client on an ELAN that performs data forwarding, address resolution & other control functions. The LEC resides on end stations in an ELAN
LED                     Light Emitting Diode - An indicator that emits light when an electrical current is passed through it
LES LAN emulation server - The central control point for an ELAN. Enables LAN emulation clients to join the ELAN and resolves LAN addresses to ATM addresses
library A data-storage system, usually managed by Removable Storage. A library consists of removable media (such as tapes or discs) and a hardware device that can read from or write to the media. There are two major types of libraries: robotic libraries (automated multiple-media, multidrive devices) and stand-alone drive libraries (manually operated, single-drive devices). aka a jukebox or changer
Li-lon Lithium Ion batteries: lightweight and can be recharged multiple times
Link Cost Cost associated with the interface. Based on this cost, the bridge decides which link to forward data over
LLC                     Logical Link Control The upper portion of the data link layer, as defined in IEEE 802.2. The LLC sublayer presents a uniform interface to the user of the data link service, usually the network layer
Lmhosts file A local text file that maps NetBIOS names (commonly used for computer names) to IP addresses for hosts that are not located on the local subnet
Load balancing A technique used by Ethernet bridges to evenly divide traffic between two channels, thus maximising throughput
Load balancing A technique used by Windows Clustering to scale the performance of a server-based program (such as a Web server) by distributing its client requests across multiple servers within the cluster. Each host can specify the load percentage that it will handle, or the load can be equally distributed across all the hosts. If a host fails, Windows Clustering dynamically redistributes the load among the remaining hosts
local group For computers running Windows and member servers, a group that can be granted permissions and rights from its own computer and (if the computer participates in a domain) user accounts and global groups both from its own domain and from trusted domains
local user A person who uses a computer that is not connected to a network. A local user is most likely someone using a computer at home
local user profile A computer-based record about an authorized user that is created automatically on the computer the first time a user logs on to a workstation or server computer
logical drive A volume that you create within an extended partition on a basic master boot record (MBR) disk. Logical drives are similar to primary partitions, except that you are limited to four primary partitions per disk, whereas you can create an unlimited number of logical drives per disk. A logical drive can be formatted and assigned a drive letter
Logical Port A method for grouping two physical ports under a single, logical port number. Logical port numbers allow the Spanning Tree Algorithm to permit the use of dual links in a parallel load-shearing configuration
logical printer The software interface between the operating system and the printer in Windows. While a printer is the device that does the actual printing, a logical printer is its software interface on the print server. This software interface determines how a print job is processed and how it is routed to its destination (to a local or network port, to a file, or to a remote print share). When you print a document, it is spooled (or stored) on the logical printer before it is sent to the printer itself
logon script Files that can be assigned to user accounts. Typically a batch file, a logon script runs automatically every time the user logs on. It can be used to configure a user's working environment at every logon, and it allows an administrator to influence a user's environment without managing all aspects of it. A logon script can be assigned to one or more user accounts
logon script path A sequence of directory names that specifies the location of the logon script. When a user logs on, the authenticating computer locates the specified logon script (if one has been assigned to that user account) by following that computer's local logon script path (usually systemroot\System32\Repl\Import\Scripts)
long name A folder name or file name longer than the 8.3 file name standard (up to eight characters followed by a period and an extension of up to three characters) of the FAT file system. XP supports long file names up to 255 characters. Windows XP auto-translates long names of files and folders to 8.3 names for MS-DOS and Windows 3.x users
long name Macintosh: users can assign long names to files and folders on the server and, using AppleTalk network integration, you can assign long names to Macintosh-accessible volumes when you create them
loopback address The address of the local computer used for routing outgoing packets back to the source computer. This address is used primarily for testing
loose name checking A form of domain name checking DNS uses that examines characters in DNS names for valid ANSI character compliance. However, loose name checking does not check for compliance with DNS naming requirements and valid character usage for Internet host names, as specified in RFC 1123, Requirements for Internet Hosts - Applications and Support

For RFC compliance, DNS domain names will use name labels made up only of valid uppercase and lowercase letters, number characters, and hyphens (A through Z, a through z, 0 through 9, and -) separated by periods

LPD Line Printer Daemon - A service on the print server that receives documents (print jobs) from Line Printer Remote (LPR) utilities running on client systems
LPR Line Printer Remote - A connectivity utility that runs on client systems and is used to print files to a computer running an LPD server

M

MAC Message Authentication Code - An algorithm that ensures the quality of a block of data
MAC address A factory-defined 48-bit number programmed into the device that is unique to each LAN device. Destination and source MAC names are contained in the LAN packet and are used by bridges to filter and forward packets
MacFile An AppleTalk network integration service that allows Macintosh clients and personal computer clients to share files. aka File Server for Macintosh
MAC Filter Method of allowing or rejecting WAN access for specific machines / PCs
MADCAP Multicast Address Dynamic Client Allocation Protocol - An extension to the DHCP protocol standard used to support dynamic assignment and configuration of IP multicast addresses on TCP/IP-based networks
management system A network-enabled host running Simple Network Management Protocol (SNMP) management software. This software requests information from SNMP agents. aka management console
MARS multicast address resolution service - A service for resolving multicast IP addresses to the ATM addresses of the clients that have joined that multicast group. The MARS can work in conjunction with the MCS and clients to distribute multicast data through point-to-multipoint connections
Martian address An illegal IP address, as designated by the IEEE. IP addresses should not begin with 0, 127, or any number above 223.
master domain A Windows NT 4.0 domain that is used for managing user and group accounts in a multidomain network
master server An authoritative DNS server for a zone. Master servers can vary and are one of two types (either primary or secondary masters), depending on how the server obtains its zone data
MAU                 Media Access Unit A device also known as a transceiver. The MAU is the physical attachment to the LAN cable. It is a medium-dependent interface that allows access to the LAN segment.
Max Age Time Timeout value that all bridged LAN bridges use. The root bridge sets the Max Age value
Mbps               Megabits per Second  - A million bits per second
MBR master boot record - The first sector on a hard disk, which starts the process of booting the computer. The MBR contains the partition table for the disk and a small amount of executable code called the master boot code
MCS multicast server - A service that manages zero or more multicast groups and distributes multicast data sent to it by clients of those multicast groups through point-to-multipoint connections
MD2 developed by RSA Data Security, a hash algorithm that creates a 128-bit hash value
MD4 developed by RSA Data Security, a hash algorithm that creates a 128-bit hash value
MD5

developed by RSA Data Security, an industry-standard one-way, 128-bit hashing scheme,  used by various Point-to-Point Protocol vendors for encrypted authentication. A hashing scheme is a method for transforming data (eg, a password) in such a way that the result is unique and cannot be changed back to its original form. The CHAP authentication protocol uses challenge-response with one-way MD5 hashing on the response. In this way, you can prove to the server that you know your password without actually sending the password over the network

ME a name i call myself
media pool  logical collection of removable media that have the same management policies. Media pools are used by applications to control access to specific tapes or discs within libraries managed by Removable Storage. There are four media pools: unrecognized, import, free, and application-specific. Each media pool can only hold either media or other media pools
media sensing A feature that, when it detects a network cable connection failure, removes the bound protocols from the failed network adapter until the cable connection is reestablished. Without these bound protocols, the network interface connected through the failed network adapter is not available for cluster communication
mediator For Process Control, a process used to preserve information when a service stops or starts
memory address A portion of computer memory that can be allocated to a device or used by a program or the operating system. Devices are usually allocated a range of memory addresses
Memory Usage In Task Manager, the current working set of a process, in kilobytes. The current working set is the number of pages currently resident in memory. On the Task Manager Processes tab, the column heading is Mem Usage
Memory Usage Delta In Task Manager, the change in memory, in kilobytes, used since the last update
message For Message Queuing, a unit of information sent between computers running Message Queuing. The message can contain text or binary data as defined by the sending application. All messages, including status messages, are stored in queues on Message Queuing computers
Message Queuing A message queuing and routing system for Windows that enables distributed applications running at different times to communicate across heterogeneous networks and with computers that may be offline. Message Queuing provides guaranteed message delivery, efficient routing, security, and priority-based messaging. aka MSMQ
Message Queuing server For Message Queuing (aka MSMQ), a computer that can provide message queuing, routing, and directory services to client computers. Message Queuing servers can be used to:
  • Provide message routing and session concentration for independent clients.
  • Provide message routing between sites over routing links.
  • Create queues and store messages for dependent clients.
  • Access information in Active Directory (if installed on a Windows domain controller)
Messenger service A service that sends and receives messages sent by administrators or by the Alerter service
metadata Data about data. eg, the title, subject, author, and size of a file constitute the file's metadata
metric A number used to indicate the cost of a route in the IP routing table that enables the selection of the best route among possible multiple routes to the same destination
MF                 [Dual Tone Multi Frequency] -The formal names for push-button or touch-tone dialing. aka DTMF
MFT Master File Table - An NTFS system file on NTFS-formatted volumes that contains information about each file and folder on the volume. The MFT is the first file on an NTFS volume
MIB Management Information Base - A set of objects that represent various types of information about a device, used by Simple Network Management Protocol (SNMP) to manage the device. Because different network management services are used for different types of devices and protocols, each service has its own set of objects
Microfilter used on a DEL that also supports ADSL, a plug in device that reduces interference between DSL signals and telephone signals
MIDI

Musical Instrument Digital Interface - A serial interface standard that allows for the connection of music synthesizers, musical instruments, and computers. The MIDI standard is based partly on hardware and partly on a description of the way in which music and sound are encoded and communicated between MIDI devices. The information transmitted between MIDI devices is in a form called a MIDI message, which encodes aspects of sound, such as pitch and volume, as 8-bit bytes of digital information.

MIDI devices can be used for creating, recording, and playing back music. Using MIDI, computers, synthesizers, and sequencers can communicate with each other, either keeping time or actually controlling the music created by other connected equipment

minimum TTL A default Time to Live (TTL) value set in seconds for use with all resource records in a zone. This value is set in the start of authority (SOA) resource record for each zone. By default, the DNS server includes this value in query answers to inform recipients how long it can store and use resource records provided in the query answer before they must expire the stored records data. When TTL values are set for individual resource records, those values will override the minimum TTL
mirror One of the two volumes that make up a mirrored volume. Each mirror of a mirrored volume resides on a different disk. If one mirror becomes unavailable (due to a disk failure, for example), Windows can use the remaining mirror to gain access to the volume's data
mirror set A fault-tolerant partition created with Windows NT 4.0 or earlier that duplicates data on two physical disks. You can only repair, resynchronize, break, or delete mirror sets in Windows 2000. To create new volumes that are mirrored, use mirrored volumes on dynamic disks
mirrored volume A fault-tolerant volume that duplicates data on two physical disks. A mirrored volume provides data redundancy by using two identical volumes, which are called mirrors, to duplicate the information contained on the volume. A mirror is always located on a different disk. If one of the physical disks fails, the data on the failed disk becomes unavailable, but the system continues to operate in the mirror on the remaining disk. You can create mirrored volumes only on dynamic disks
MIS                 Management Information System - A computer-based information system that integrates data from all the departments that it serves in order to provide operations and management with the information they need
MMS Multi Messaging Service
MMC MultiMedia Card
MMC Microsoft Management Console - A framework for hosting administrative tools, called consoles. A console may contain tools, folders or other containers, World Wide Web pages, and other administrative items. These items are displayed in the left pane of the console, called a console tree. A console has one or more windows that can provide views of the console tree.

The main MMC window provides commands and tools for authoring consoles. The authoring features of MMC and the console tree itself may be hidden when a console is in User Mode

MNP4 Microcom Networking Protocol Four - An industry-standard communication protocol that allows modems to automatically retransmit corrupted data, assuring that only error-free data passes through the modem. MNP2 and MNP3 standards are included in MNP4
MNP5 Microcom Networking Protocol Five - A data-compression standard that allows modems to increase throughput by compressing data before transmission. Data can be compressed with a ratio of up to 2:1. MNP5 sometimes expands data that has already been compressed, resulting in poorer performance in those cases. If you have an MNP5 modem, do not turn on modem compression and software compression at the same time. To turn on MNP5 compression, you must also turn on MNP4 error control
Modem           Modulator / Demodulator - A device that allows the transmission of data over the telephone network. The transmitting modem translates digital computer data into analog signals that can be carried over the phone line. The receiving modem translates the analog signals back to digital
modem compression A technique used to reduce the number of characters transmitted without losing data content. The transmitting modem compresses the data and the receiving computer or modem decompresses the data back to its original state
Modulation Varying elements of electrical carrier waves in a manner that represents signal data. Demodulation restores the signal data. A modulated signal requires more bandwidth and an unmodulated signal does. The bandwidth increase results from the creation of sidebands during modulation. The sidebands contain the signal. AM creates two, identical sidebands on either side of the carrier. FM creates an infinite number of sidebands
modulation standards Protocols that determine how modems convert digital data into analog signals that can be transmitted over telephone lines. Initially, Bell created modulation standards used in the United States, and the CCITT created international recommendations. The ITU-T (formerly called the CCITT) now makes recommendations generally adopted by modem manufacturers both internationally and in the United States. The ITU-T V series recommendations (such as V.34 and V.90) define data communication over the telephone network. The suffixes -bis and -ter (eg, V.32bis) indicate later versions
mount To place a removable tape or disc into a drive
mounted drive A drive attached to an empty folder on an NTFS volume. Mounted drives function the same as any other drive, but are assigned a label or name instead of a drive letter. The mounted drive's name is resolved to a full file system path instead of just a drive letter. Members of the Administrators group can use Disk Management to create mounted drives or reassign drive letters
MP               Multilink PPP A protocol that bundles multiple links (logical or physical) into one logical link with greater bandwidth than any of the original links. Data fragmentation in the PPP Multilink algorithm ensures optimal utilisation and load - sharing of the bandwidth of both links by splitting a data frame into multiple tiny subframes  and spreading them out over the physical links.
MPPE Microsoft Point-to-Point Encryption - A 128-bit key or 40-bit key encryption algorithm using RSA RC4. MPPE provides for packet confidentiality between the remote access client and the remote access or tunnel server and is useful where IP security (IPSec) is not available. MPPE 40-bit keys are used to satisfy current North American export restrictions. MPPE is compatible with Network Address Translation
MS-DOS

Microsoft Disk Operating System - An operating system used on PCs and compatibles. Translates user keyboard input into operations the computer can perform. MS-DOS can be easily accessed by using the command prompt, while MS-DOS-based programs can be accessed through the use of shortcuts on the desktop

MS-DOS-based program A program that is designed to run with MS-DOS
MS-CHAP           Microsoft has created a Windows-specific variant of CHAP [Challenge Handshake Authentication Protocol] - which is an authentication protocol in which the authenticator sends a challenge message to verify the identity of a remote user. PPP calls must go through CHAP
MS DTC Microsoft Distributed Transaction Coordinator - A transaction manager that coordinates transactions that span multiple resource managers, such as Message Queuing and Microsoft SQL Server. MS DTC is automatically installed when Message Queuing is installed
MSR partition Microsoft Reserved partition - A required partition on every GUID partition table (GPT) disk. System components can allocate portions of the MSR partition into new partitions for their own use. eg, when you convert a basic GPT disk to dynamic, the system allocates a portion of the MSR partition to be used as the Logical Disk Manager (LDM) metadata partition. The MSR partition varies in size based on the size of the GPT disk. For disks smaller than 16 GB, the MSR partition is 32 MB. For disks larger than 16 GB, the MSR partition is 128 MB. The MSR partition is not visible in Disk Management, and you cannot store data on the MSR partition or delete it
MTU Maximum Transmission Unit - Parameter that limits the size of packets that transmit on an interface. Not all interfaces support the MTU parameter. Some interfaces, like Ethernet, have range restrictions (80 - 1500)
Multicast A technique that transmits a message to multiple recipients at the same time. Multicasting is used in teleconferencing and data communications networks
multicast scope A range of multicast group IP addresses in the Class D address range that are available to be leased or assigned to multicast DHCP clients by DHCP
multicast server MCS - A service that manages zero or more multicast groups and distributes multicast data sent to it by clients of those multicast groups through point-to-multipoint connections
multicasting The process of sending a message simultaneously to more than one destination on a network
multihomed computer A computer that has multiple network adapters or that has been configured with multiple IP addresses for a single network adapter
multilink dialing The combination of two or more physical communications links' bandwidth into a single logical link to increase your remote access bandwidth and throughput by using remote access Multilink. Based on the Internet Engineering Task Force (IETF) standard RFC 1990, Multilink combines analog modem paths, ISDN B-channels, and mixed analog and digital communications links on both your client and server computers. This increases your Internet and intranet access speed and decreases the amount of time you are connected to a remote computer
multiple boot A computer configuration that runs two or more operating systems
multimaster replication A replication model in which any domain controller accepts and replicates directory changes to any other domain controller. This differs from other replication models in which one computer stores the single modifiable copy of the directory and other computers store backup copies

N

name resolution The process of having software translate between names that are easy for users to work with and numerical IP addresses, which are difficult for users but necessary for TCP/IP communications. Name resolution can be provided by software components such as DNS or WINS
name server (NS) resource record A resource record used in a zone to designate the DNS domain names for authoritative DNS servers for the zone
named pipe A portion of memory that can be used by one process to pass information to another process, so that the output of one is the input of the other. The second process can be local (on the same PC as the first) or remote (on a networked PC)
namespace A set of unique names for resources or items used in a shared computing environment
namespace Microsoft Management Console (MMC), the namespace is represented by the console tree, which displays all of the snap-ins and resources that are accessible to a console
namespace Domain Name System (DNS), namespace is the vertical or hierarchical structure of the domain name tree. For example, each domain label, such as host1 or example, used in a fully qualified domain name, such as host1.example.microsoft.com, indicates a branch in the domain namespace tree
NAP Network Access Point - Public network exchange facility where ISPs connect while peering. NAP connections determine how the Internet routes traffic
NAPT Network Address Port Translation
NAT                Network Address translation - translation of IP addressing to network ip addresses 
native mode The condition in which all domain controllers in the domain have been upgraded to Windows 2000 and an administrator has enabled native mode operation (through Active Directory Users and Computers)
NCP NetWare Core Protocol - The file-sharing protocol that governs communications about resource (such as disk and printer), bindery, and NDS operations between server and client computers on a Novell NetWare network. Requests from client computers are transmitted by the IPX protocol. Servers respond according to NCP guidelines
NDS Novell Directory Services - On networks running Novell NetWare 4.0, a distributed database that maintains information about every resource on the network and provides access to these resources
NetBEUI NetBIOS Extended User Interface - A network protocol native to Microsoft Networking. It is usually used in small, department-size local area networks (LANs) of 1 to 200 clients. It can use Token Ring source routing as its only method of routing. It is the Microsoft implementation of the NetBIOS standard
NetBIOS network basic input/output system - An application programming interface (API) that can be used by programs on a local area network (LAN). NetBIOS provides programs with a uniform set of commands for requesting the lower-level services required to manage names, conduct sessions, and send datagrams between nodes on a network
network A group of computers and other devices, such as printers and scanners, connected by a communications link, enabling all the devices to interact with each other. Networks can be small or large, permanently connected through wires or cables, or temporarily connected through phone lines or wireless transmissions. The largest network is the www, which is a worldwide group of networks
network adapter A device that connects your computer to a network. This device is sometimes called an adapter card or network interface card
network administrator A person responsible for planning, configuring, and managing the day-to-day operation of the network. aka system administrator
network card driver A device driver that works directly with the network card, acting as an intermediary between the card and the protocol driver. With AppleTalk network integration, the AppleTalk Protocol stack on the server is implemented as a protocol driver and is bound to one or more network card drivers
Network Connections A component you can use to gain access to network resources and functionality, whether you are physically at the network location or in a remote location. By using the Network Connections folder you can create, configure, store, and monitor connections
Network DDE service A service that provides network transport and security for DDE conversations
network media The type of physical wiring and lower-layer protocols used for transmitting and receiving packets; eg, Ethernet, FDDI, and Token Ring
Network Name resource The name of a device that exists on a network and is supported as a cluster resource by a Resource DLL provided with Windows
network number Macintosh: the routing address or range of addresses assigned to the physical network that AppleTalk Phase 2 routers use to direct information to the appropriate network. aka network range and cable range
network partition A state in which one or more of the nodes in a cluster cannot communicate with the other cluster nodes
network place A folder on a Web server. You can view files and folders on Web servers just as you would view files and folders on network servers. However, when you save a file to a network place, the file is saved on a Web server, not on your computer's hard disk. You can create network places by using the Add Network Place Wizard, which is located in My Network Places. Network places are available only on Web servers that support Web Extender Client (WEC), FrontPage extensions, and Distributed Authoring and Versioning (DAV) protocols
Next Hop IP IP address or Gateway used to arrive at the destination address
NTFS file system

An advanced file system that provides performance, security, reliability &advanced features that are not found in any version of FAT. eg, NTFS guarantees volume consistency by using standard transaction logging and recovery techniques. If a system fails, NTFS uses its log file and checkpoint information to restore the consistency of the file system. In Windows 2000 and Windows XP, NTFS also provides advanced features such as file and folder permissions, encryption, disk quotas, and compression

NIC                Network Interface Card - NIC is also known as a network adapter, a LAN Adapter, or a LAN card. Usually, a PC expansion board executes the code needed by the connected device to share a cable or some other media with other stations.
NMS network management system - A combination of hardware and software that allows the network manager to configure the network, perform traffic analysis, detect and correct faults, and perform regular network maintenance. NMS systems typically manage large networks containing combinations of LAN servers, concentrators, bridges, routers, and repeaters.
NNTP

Network News Transfer Protocol - A member of the TCP/IP suite of protocols used to distribute network news messages to NNTP servers and clients (newsreaders) on the Internet. NNTP is designed so that news articles are stored on a server in a central database enabling a user to select specific items

node A connection point for two or more communications links. The node serves as the control location for forwarding data among the elements of a network or multiple networks. In some cases, it performs local processing functions
nonauthoritative restore A restore of a backup copy of a Windows domain controller in which the objects in the restored directory are not treated as authoritative. The restored objects are updated with changes held in other replicas of the restored domain
noncontainer object An object that cannot logically contain other objects. eg, a file is a noncontainer object
nonhubbed mode A mode in which the ATM ARP/MARS does not forward multicast and broadcast traffic for multicast group clients. In this mode, the service returns a dynamic listing of ATM hosts currently registered for the multicast group address to requesting clients. Clients then use this list to initiate and establish their own point-to-multipoint virtual connections with each of the members in the multicast list
nonpaged memory Memory that cannot be paged to disk. Paging is the moving of infrequently used parts of a program's working memory from RAM to another storage medium, usually the hard disk
nonpaged pool Operating system memory that is never paged to disk. Paging is the moving of infrequently used parts of a program's working memory from RAM to another storage medium, usually the hard disk. In Task Manager, the amount of memory used by a process, in kilobytes
normal backup A backup that copies all selected files and marks each file as having been backed up (in other words, the archive attribute is cleared). With normal backups, you need only the most recent copy of the backup file or tape to restore all of the files. You usually perform a normal backup the first time you create a backup set
notify list A list maintained by the primary master for a zone of other DNS servers that should be notified when zone changes occur. The notify list is made up of IP addresses for DNS servers configured as secondary masters for the zone. When the listed servers are notified of a change to the zone, they will initiate a zone transfer with another DNS server and update the zone
NRT-VBR Non Real Time-Variable Bit Rate - Service type that supports applications that have no constraints on delay & delay variation, but still have variable-rate and burst traffic characteristics
Nslookup A command-line tool used to diagnose Domain Name System (DNS) infrastructure
NTDS-DSA object

An object that represents the configuration of the Active Directory service running on a specific domain controller. eg, the NTDS-DSA object holds the setting that determines whether or not the Active Directory service provides global catalog services. NTDS-DSA objects are created and deleted in the course of running the Active Directory Installation Wizard (dcpromo.exe).

An NTDS-DSA object is stored in the Configuration directory partition and is always a child of the Server object representing the domain controller where this particular Active Directory service is running.

eg, if the distinguished name of an NTDS-DSA object is:

  • CN=NTDS Settings, CN=RESKIT1,CN=Servers, CN=Washington, CN=Sites, CN=Configuration, DC=reskit,DC=com

then the distinguished name of the corresponding Server object is:

  • CN=RESKIT1, CN=Servers, CN=Washington, CN=Sites,
    CN=Configuration, DC=reskit, DC=com

NTLM

A security package that provides authentication between clients & servers

NTLM authentication protocol

The NTLM challenge/response protocol was the default for network authentication in Windows NT version 4.0 and earlier

null modem cable

Special cable / lead that eliminates the modem's need for asynchronous communications between two computers over short distances. A null modem cable emulates modem communication

NVRAM             Non-volatile Random Access memory - A type of PC memory that does not lose data when the PC is powered off, and can function like traditional RAM when power is applied
NWLink

An implementation of the Internetwork Packet Exchange (IPX), Sequenced Packet Exchange (SPX), and NetBIOS protocols used in Novell networks. NWLink is a standard network protocol that supports routing and can support NetWare client-server applications, where NetWare-aware Sockets-based applications communicate with IPX/SPX Sockets-based applications

O

object

An entity, such as a file, folder, shared folder, printer, or Active Directory object, described by a distinct, named set of attributes. eg, the attributes of a File object include its name, location, and size; the attributes of an Active Directory User object might include the user's first name, last name, and e-mail address.

For OLE and ActiveX, an object can also be any piece of information that can be linked to, or embedded into, another object

octet An 8-bit byte.
OLE A way to transfer and share information between applications by pasting information created in one application into a document created in another application, such as a spreadsheet or word processing file
on-disk catalog Information stored on a local disk drive. The on-disk catalog contains a list of files and folders that have been backed up in a backup set
on-media catalog Information stored on backup storage media. The on-media catalog contains a list of files and folders that have been backed up in a backup set.
one-way trust A type of trust relationship in which only one of the two domains trusts the other domain. eg, domain A trusts domain B and domain B does not trust domain A. All one-way trusts are nontransitive
online A state that marks a component in a cluster as available. When a node is online, it is an active member of the cluster and can own and run groups as well as honor cluster database updates, contribute votes to the quorum algorithm, and maintain heartbeats. Resources and groups also have an online state
operations master

 

A domain controller that has been assigned one or more special roles in an Active Directory domain. The domain controllers assigned these roles perform operations that are single-master (not permitted to occur at different places on the network at the same time). Examples of these operations include resource identifier allocation, schema modification, PDC election, and certain infrastructure changes. The domain controller that controls the particular operation owns the operations master role for that operation. The ownership of these operations master roles can be transferred to other domain controllers
organizational unit An Active Directory container object used within domains. An organizational unit is a logical container into which users, groups, computers, and other organizational units are placed. It can contain objects only from its parent domain. An organizational unit is the smallest scope to which a Group Policy object can be linked, or over which administrative authority can be delegated
orphan A member of a mirrored volume or a RAID-5 volume that has failed due to a severe cause, such as a loss of power or a complete hard-disk head failure. When this happens, the fault-tolerant driver determines that it can no longer use the orphaned member and directs all new reads and writes to the remaining members of the fault-tolerant volume
orphan file A file that is stored inside My Briefcase and not linked to any file outside My Briefcase. When you update files, the orphan file is not synchronized with any other file
OSI Open System Interconnection - A set of international standards governing interconnection of multiple vendors' architecture. OSI standards are enforced by the International Organisation for Standardisation (ISO) and the Telecommunication Standardisation Sector (TSS)
OSI Reference Model An architectural framework used to describe the structure and function of data communications protocols. The model consists of seven layers [each layer represents a function performed when data is transferred between applications on a network]:
  1. the physical layer,
  2. the data link layer,
  3. the network layer,
  4. the transport layer,
  5. the session layer,
  6. the presentation layer,
  7. the application layer.
OS/2 A protected-mode, virtual memory, multitasking operating system for personal computers based on the Intel 80286, 80386, i486, and Pentium processors. OS/2 can run most MS-DOS-based programs and can read all MS-DOS disks
Owner Windows: the person who controls how permissions are set on objects and can grant permissions to others
Owner Macintosh: an owner is the user responsible for setting permissions for a folder on a server. A Macintosh user who creates a folder on the server automatically becomes the owner of the folder, and can then transfer ownership to someone else. Each Macintosh-accessible volume on the server also has an owner.
owner category Macintosh: the user category to which you assign permissions for the owner of a folder or a Macintosh volume

P

Packet An Open Systems Interconnection (OSI) network layer transmission unit that consists of binary information representing both data and a header containing an identification number, source and destination addresses, and error-control data
packet filtering The recognition and selective transmission or blocking of packets based on destination addresses or other packet contents.
packet header In network protocol communications, a specially reserved field of a defined bit length that is attached to the front of a packet for carry and transfer of control information. When the packet arrives at its destination, the field is then detached and discarded as the packet is processed and disassembled in a corresponding reverse order for each protocol layer
packet switching A technology for breaking data into packets and then sending the packets over a network. Each packet has a header containing its source and destination, a sequence number to reassemble the information, a block of data content, and an error-checking code. The data packets may take different routes to their destination, where the original information is reassembled after the packets arrive. The international standard for packet switching networks is X.25
PAD

packet assembler/disassembler - A device that connects a non-X.25 device such as a modem to an X.25 packet switching network

paged pool The system-allocated virtual memory that has been charged to a process and that can be paged. Paging is the moving of infrequently-used parts of a program's working memory from RAM to another storage medium, usually the hard disk
paging file A hidden file on the hard disk that Windows uses to hold parts of programs and data files that do not fit in memory. The paging file and physical memory, or RAM, comprise virtual memory. Windows moves data from the paging file to memory as needed and moves data from memory to the paging file to make room for new data. aka swap file
PAM Pulse Amplitude Modulation - Modulation method used by modems and DSL equipment. The signal modulates or alters the amplitude or intensity of the carrier. In regular AM, the carrier is a sinewave. In PAM, the carrier is a periodic series of DC pulses
PAN Personal Area Network
PAP                 Password Authentication protocol - A simple, plaintext authentication scheme for authenticating PPP connections. The user name and password are requested by the remote access server and returned by the remote access client in plaintext. PAP is an authentication phase that PPP calls must go through. In PAP, the ID and the Password pair is sent repeatedly by the user to the authenticator until authentication is acknowledged or the connection is terminated
parallel port The input/output connector for a parallel interface device eg a printer
parent domain For DNS and Active Directory, domains that are located in the namespace tree directly above other derivative domain names (child domains). eg, microsoft.com would be the parent domain for example.microsoft.com, a child domain
parent object The object in which another object resides. A parent object implies relation. For example, a folder is a parent object in which a file, or child object, resides. An object can be both a parent and a child object. For example, a subfolder that contains files is both the child of the parent folder and the parent folder of the files.
parity A calculated value that is used to reconstruct data after a failure. RAID-5 volumes stripe data and parity intermittently across a set of disks. When a disk fails, some server operating systems use the parity information together with the data on good disks to recreate the data on the failed disk
parity bit In asynchronous communications, an extra bit used in checking for errors in groups of data bits transferred within or between computer systems. In modem-to-modem communications, a parity bit is often used to check the accuracy with which each character is transmitted
partition A portion of a physical disk that functions as though it were a physically separate disk. After you create a partition, you must format it and assign it a drive letter before you can store data on it.

On basic disks, partitions are known as basic volumes, which include primary partitions and logical drives. On dynamic disks, partitions are known as dynamic volumes, which include simple, striped, spanned, mirrored, and RAID-5 volumes

partition boot sector A portion of a hard disk partition that contains information about the disk's file system and a short machine language program that loads the Windows operating system
Partitioning The division of a LAN into two or more distinct segments joined by a bridge. Partitioning can reduce LAN media loading by localising traffic and increase reliability by isolating LAN segments
PBX Private Branch Exchange [aka telephone system] A system of connection of telephone lines that serves a particular organisation and uses telephone services rather than supplies them
PC Card

 removable, credit card sized, device that can be plugged into a Personal Computer Memory Card International Association (PCMCIA) slot in a portable computer. PCMCIA devices can include modems, network cards, and hard disk drives

PCI

peripheral component interconnect - A specification introduced by Intel that defines a local bus system that allows up to 10 PCI-compliant expansion cards to be installed in the computer - a high performance 32-bit or 64-bit bus designed to be used with devices that have high bandwidth requirements, such as a display subsystem

PCI Pre Connection Inspection - an inspection carried out by the PSTN providor prior to connection of PBX switches. no loner required in the UK

PCI expansion slot

A connection socket for a peripheral designed for the PCI local bus on a PC motherboard

PCL Printer Control Language - The page-description language (PDL) developed by Hewlett Packard for their laser & inkjet printers. This command language has become a standard in many printers
PCM Pulse Code Modulation - Digital modulation method for transmitting analog data. PCM signals are binary. These signals can represent any analog data with only two states, logic 0 and logic 1
PCMCIA Personal Computer Memory Card International Association: the body for setting the standards for the mobile computer slots that accommodate data cards, now referred to as PC Cards
PDM Pulse Duration Modulation - Modulation method. Signal modulates or alters the duty cycle of the pulse. In PDM, the carrier is a pulse stream. aka PWM (Pulse Width Modulation).
PDA Personal Digital Assistant
PDC primary domain controller - In a Windows NT Server 4.0 or earlier domain, the computer running Windows NT Server that authenticates domain logons and maintains the directory database for a domain. The PDC tracks changes made to accounts of all computers on a domain. It is the only computer to receive these changes directly. A domain has only one PDC. In this version of Windows, one of the domain controllers in each domain is identified as the PDC for compatibility with Windows NT 4.0 and earlier versions of Windows NT
PDC emulator master

The domain controller assigned to act as a Windows NT 4.0 primary domain controller (PDC) to service network clients that do not have Active Directory client software installed, and to replicate directory changes to any Windows NT backup domain controllers (BDCs) in the domain. The PDC emulator master receives preferential replication of password changes performed by other domain controllers in the domain and handles any password authentication requests that fail at the local domain controller. At any time, there can be only one PDC emulator master in a particular domain

PDL page-description language - A computer language that describes the arrangement of text and graphics on a printed page
Peak Cell Rate Maximum rate (Cells/second) for sending cells to the network
Per Seat Licensing A licensing mode that requires a separate Client Access License for each client computer, regardless of whether all the clients access the server at the same time
Per Server Licensing A licensing mode that requires a separate Client Access License for each concurrent connection to the server, regardless of whether there are other client computers on the network that do not happen to connect concurrently
Phase Position of a periodic waveform
PM Phase Modulation - Modulation method used by modems, radio, and DSL equipment. The signal modulates or alters the phase or position of carrier waves. In regular PM, the carrier is a sinewave. The phase of the modulated carrier changes in proportion to signal amplitude
PID

process identifier - A numerical identifier that uniquely distinguishes a process while it runs. Use Task Manager to view PIDs

PIF program information file - A file that provides information to Windows about how best to run MS-DOS-based programs. When you start an MS-DOS-based program, Windows looks for a PIF to use with it. PIFs contain such items as the name of the file, a start-up directory, and multitasking options: DO NOT OPEN AN EMAIL CONTAINING A PIF
PING                Packet Internet Groper - A internetworking debug and diagnostic program. When trying to determine the accessibility of a device (a router or a PC), a PING is sent to the IP address of that device. The sender then waits for a response that verifies connection. The ping command uses the ICMP echo request and echo reply packets to determine whether a particular IP system on a network is ok
PIM Personal Information Management
PJL Printer Job Language - The printer command language developed by Hewlett Packard that provides printer control at the print-job level. Using PJL commands, you can change default printer settings such as number of copies to print. PJL commands also permit switching printer languages between print jobs without action by the user. If bi-directional communication is supported, a PJL-compatible printer can send information such as printer model and job status to the print server
PKCS Public Key Cryptography Standards - Developed, owned & maintained by RSA Data Security, Inc: a family of standards for public key cryptography that includes RSA encryption, Diffie-Hellman key agreement, password-based encryption, extended-syntax, cryptographic message syntax, private key information syntax, and certificate request syntax, as well as selected attributes
PKCS #10 Certification Request Syntax Standard: A syntax for certificate requests.
PKCS #12 Personal Information Exchange Syntax Standard - This syntax standard specifies a portable format for storing or transporting a user's private keys, certificates, and miscellaneous secrets
PKCS #7 Cryptographic Message Syntax Standard - a general syntax, for data to which cryptography may be applied, such as digital signatures and encryption. It also provides a syntax for disseminating certificates or certificate revocation lists.
PKI  

public key infrastructure - The term generally used to describe the laws, policies, standards, and software that regulate or manipulate certificates and public and private keys. In practice, it is a system of digital certificates, certification authorities, and other registration authorities that verify and authenticate the validity of each party involved in an electronic transaction. Standards for PKI are still evolving, even though they are being widely implemented as a necessary element of electronic commerce

Plug and Play

A set of Intel specifications by that allows a PC to automatically detect & configure a device with the required drivers

policy

The mechanism by which desktop settings are configured automatically, as defined by the administrator. Depending on context, this can refer to Group Policy, Windows NT 4.0 System Policy, or a specific setting in a Group Policy object

polling intervals The frequency the Resource Monitor checks that the resource is available and operating. There are two levels of polling: Looks Alive and Is Alive. The server cluster requests a more thorough check of the resource's state at each Is Alive interval than it does at each Looks Alive interval; therefore, the Is Alive polling interval is typically longer than the Looks Alive polling interval. You can specify the two polling intervals and a time-out value for resources
POP3

Post Office Protocol 3 - protocol used for receiving e-mails. Favoured by ISPs, POP3 servers allow access to a single Inbox in contrast to IMAP servers, which provide access to multiple server-side folders

port a communications interface on a host computer or the communications interface of a pbx [eg an extension]
Port Priority Parameter that determines which port becomes the root bridge port
port rule Network Load Balancing - a set of configuration parameters that determine the filtering mode to be applied to a range of ports
POS/EFT terminals Point of Sales/Electronic Funds Transfer
POSIX Portable Operating System Interface for UNIX - An IEEE standard that defines a set of operating-system services. Programs that adhere to the POSIX standard can be easily ported from one system to another. POSIX was based on UNIX system services, but it was created in a way that allows it to be implemented by other operating systems
possible owners A list that specifies which nodes in the cluster are capable of running that resource. By default, both nodes appear as possible owners, so the resource can run on either node. In most cases, it is appropriate to use this default setting. If you want the resource to be able to fail over, both nodes must be designated as possible owners
PostScript A page-description language (PDL), developed by Adobe Systems for printing on laser printers. PostScript offers flexible font capability and high-quality graphics. It is the standard for desktop publishing because it is supported by imagesetters, the high-resolution printers used by printing services for commercial typesetting
PostScript printer A printer that uses the PostScript page-description language (PDL) to create text and graphics on the output medium, such as paper or overhead transparency
POT            Plain Old Telephone - a standard, analogue 2wire device, usually a 'phone [ie not a digital proprietary 'phone] 
POTS                Plain Old Telephone Service - The POTS started as a human-operated analogue circuit switching system (plugboards), was later based on electromechanical switches, and is now almost entirely digitally-based, except for the final connection to the subscriber
POTS point of termination station - Basic dial telephone connections to the public switched network, without any added features or functions. Plain old telephone service and point of termination station is also called POTS
PP Point-to-Point Protocol -  communications protocol that allows a computer to use TCP/IP with a standard telephone line and a high-speed modem. PPP establishes the session between the user’s computer and the ISP. PPP is a new standard that replaces SLIP. It can also run on any full-duplex link from dial-up to high-speed DS1 and DS3 lines. PPP uses the Link Control Protocol (LCP), which also handles authentication (PAP, CHAP etc.), compression & encryption
Ppm Pages per minute
PPM Pulse Position Modulation - Modulation method used by modems and DSL equipment. The signal modulates or alters the location of a pulse in the carrier. The carrier is a stream of pulses.
PPP               Point-to-Point Protocol -  communications protocol that allows a computer to use TCP/IP with a standard telephone line and a high-speed modem. PPP establishes the session between the user’s computer and the ISP. PPP is a new standard that replaces SLIP. It can also run on any full-duplex link from dial-up to high-speed DS1 and DS3 lines. PPP uses the Link Control Protocol (LCP), which also handles authentication (PAP, CHAP, etc.), compression & encryption
PPPoA  Point-to-Point Over ATM – Dial-up Internet connections typically use PPP protocol. PPPoA is a method for running PPP protocol over ATM. PPPoA… ·

·  offers service providers similar billing and access control with a presence in dial-up services.

·  provides session authentication using Password Authentication Protocol (PAP).

·  provides session authentication using Challenge Handshake Authentication Protocol (CHAP).

·  achieves session accounting and conservation of bandwidth by closing down unused sessions.

·  allows the IAD/Router and ISP link to easily negotiate network parameters

PPPoE Point-to-Point Over Ethernet A specification for connecting users on an Ethernet network to the Internet through a broadband connection, such as a single DSL line, wireless device, or cable modem. Using PPPoE and a broadband modem, LAN users can gain individual authenticated access to high-speed data networks. By combining Ethernet and Point-to-Point Protocol (PPP), PPPoE provides an efficient way to create a separate connection for each user to a remote server.Dial-up Internet connections typically use PPP protocol.

PPPoE is the main method for running PPP protocol over Ethernet. PPPoE:

·  offers service providers similar billing and access control with a presence in dial-up services.

·  provides a low-cost solution to multiple host maintenance at the customer premises.

·  provides session authentication using Password Authentication Protocol (PAP).

·  provides session authentication using Challenge Handshake Authentication Protocol (CHAP).

·  achieves session accounting & conservation of bandwidth by closing down unused sessions.

·  allows the IAD/Router and ISP link to easily negotiate network parameters

PPTP

Point-to-Point Tunneling Protocol - Networking technology that supports multiprotocol virtual private networks (VPNs), enabling remote users to access corporate networks securely across the Internet or other networks by dialing into an Internet service provider (ISP) or by connecting directly to the Internet. The Point-to-Point Tunneling Protocol (PPTP) tunnels, or encapsulates, IP, IPX, or NetBEUI traffic inside of IP packets. This means that users can remotely run applications that are dependent upon particular network protocols

preferred owner

The node on which you prefer each group to run. eg, the static load balancing model performs best when groups are appropriately balanced between two nodes. When a node fails, the remaining node takes over the groups from the failed node, but performance is diminished. By setting those groups to fail back to their preferred server (the failed node), you automatically restore maximum performance when failback occurs. A group does not fail back if a preferred owner is not selected.

You will not always choose a preferred owner because it may not matter where the group resides; all that matters is that the group is still running on one of the two nodes. Or, the nodes may be equally capable of handling the load required to use some or all of the resources

preferred server The NetWare server that you connect to by default when you log on to your computer. The preferred server validates your user credentials and is queried when you request information about resources available on the NetWare network
preset-to callback A form of security in which a remote access server verifies users by calling them back at numbers supplied by the network administrator at the time user privileges are granted. Only a network administrator can change a preset callback number. This ensures that no one can borrow a user's password and connect to the server from a location other than the user's normal one
Protocol Filtering A feature available in some network bridges in which the bridge can be programmed to automatically forward or reject transmissions associated with specified protocols.
Protocol prioritisation A process in which the bridge orders a WAN output queue in order of priorities, based on protocol types
Private Line A telecommunications channel leased between 2 or more service points within one exchange or between different exchanges, usually at a monthly rate. aka dedicated circuit or a Leased line

Primary disk

The hard disk drive that contains the system and boot partitions used to start Windows

primary master

An authoritative DNS server for a zone that can be used as a point of update for the zone. Only primary masters have the ability to be updated directly to process zone updates, which include adding, removing, or modifying resource records that are stored as zone data. Primary masters are also used as the first sources for replicating the zone to other DNS servers

primary partition

aka volumes - A type of partition that you can create on basic disks. A primary partition is a portion of a physical disk that functions as though it were a physically separate disk. On basic master boot record (MBR) disks, you can create up to four primary partitions on a basic disk, or three primary partitions and an extended partition with multiple logical drives. On basic GPT disks, you can create up to 128 primary partitions

priority Process Control: the relative ranking of a process or process group with respect to the use of CPU and system resources. You can configure this in the Process Control snap-in
private key The secret half of a cryptographic key pair that is used with a public key algorithm. Private keys are typically used to decrypt a symmetric session key, digitally sign data, or decrypt data that has been encrypted with the corresponding public key
private network A cluster network that supports only node-to-node communication
private queue Message Queuing: a queue that is not published in Active Directory and can be accessed only by applications that have access to the full format name of the queue
Protective MBR The first sector of a GUID partition table (GPT) disk that is structured like the first sector of a master boot record (MBR) disk to prevent x86-based disk utilities from destroying GPT partitions. The Protective MBR contains one partition that reserves the entire space used on the disk by GPT partitions
protocol A set of rules and conventions for sending information over a network. These rules govern the content, format, timing, sequencing, and error control of messages exchanged among network devices
Proxy ARP         Proxy Address Resolution Protocol - A simulation of the ARP protocol used by hosts that do not support IP subnet routing, but have an interface on a subnetted network
PSTN              Public Switched Telephone network - ie BT.
PTR resource record pointer resource record - A resource record used in a reverse lookup zone created within the in-addr.arpa domain to designate a reverse mapping of a host IP address to a host DNS domain name
public key The nonsecret half of a cryptographic key pair that is used with a public key algorithm. Public keys are typically used when encrypting a session key, verifying a digital signature, or encrypting data that can be decrypted with the corresponding private key
public key cryptography A method of cryptography in which two different keys are used: a public key for encrypting data and a private key for decrypting data. aka asymmetric cryptography
public key encryption aka asymmetric encryption - A method of encryption that uses two encryption keys that are mathematically related. One key is called the private key and is kept confidential. The other is called the public key and is freely given out to all potential correspondents. In a typical scenario, a sender uses the receiver's public key to encrypt a message. Only the receiver has the related private key to decrypt the message. The complexity of the relationship between the public key and the private key means that, provided the keys are long enough, it is computationally infeasible to determine one from the other
public network A cluster network that supports client-to-cluster communication (with or without supporting node-to-node communication)
public queue Message Queuing: a queue that is published in Active Directory and replicated throughout a Windows enterprise. Public queues can, therefore, be located by any computer running Message Queuing
pulse dialing A form of dialing by means of pulse frequencies. rotary dial phones use pulse dialing
PVC Permanent Virtual Circuit - Frame relay and ATM networking term: Virtual connection between two fixed endpoints on the network
PWM Pulse Width Modulation - Modulation method. Signal modulates or alters the duty cycle of the pulse. In PWM, the carrier is a pulse stream. aka PDM (Pulse Duration Modulation).

Q

QAM Quadrature Amplitude Modulation - Modulation method used by modems & DSL equipment. Combines two amplitude-modulated (AM) signals into a single channel. The modem inserts the signals 90 degrees (one-quarter cycle) out of phase with each other. QAM modulates both carrier phase and amplitude: Doubles effective bandwidth
query Indexing Service: a structured statement that specifies the documents you want to find. The simplest query is a single word
Queue A temporary holding place for data, usually in the memory of a computer
queue A list of programs or tasks waiting for execution. In Windows printing terminology, a queue refers to a group of documents waiting to be printed. In NetWare and OS/2 environments, queues are the primary software interface between the application and print device; users submit documents to a queue. With Windows, however, the printer is that interface; the document is sent to a printer, not a queue
queue quota Message Queuing: the storage size limit for messages in public queues. When a queue quota is reached, Message Queuing can no longer send messages to that queue until one or more messages are removed from the queue. Message Queuing enforces the computer quota before it enforces the queue quota on a computer
queue type Message Queuing: a globally unique identifier (GUID) specified by the application that created the queue
quiet answer A telephone-answering protocol in which incoming calls are answered with silence instead of a tone signal. Some telephone-switching systems use quiet answering. These switching systems expect the caller to provide another phone number, code, or extension after the quiet answer
quorum disk The cluster disk on which configuration data is maintained in the quorum log, cluster database checkpoint, and resource checkpoints. The quorum disk is managed by the Quorum resource, which is usually a special kind of Physical Disk resource
quorum log The log where the quorum resource stores data. This data is maintained by the clustering software. Also known as the recovery log or change log
quorum resource The quorum-capable resource selected to maintain the configuration data necessary for recovery of the cluster. This data contains details of all of the changes that have been applied to the cluster database. The quorum resource is generally accessible to other cluster resources so that any cluster node has access to the most recent database changes. By default there is only one quorum resource per cluster

R

RADIUS

Remote Authentication Dial-In User Service - A security authentication protocol based on clients and servers and widely used by Internet service providers (ISPs) on remote servers in non-Windows-brand operating systems. RADIUS is the most popular way of authenticating and authorizing dial-up & tunnelled network users

RAID Redundant Array of Independent Disks - A method used to standardize and categorize fault-tolerant disk systems. RAID levels provide various mixes of performance, reliability, and cost. Some servers provide three of the RAID levels: Level 0 (striping), Level 1 (mirroring), and Level 5 (RAID-5)
RAID-5 volume A fault-tolerant volume with data and parity striped intermittently across three or more physical disks. Parity is a calculated value that is used to reconstruct data after a failure. If a portion of a physical disk fails, Windows recreates the data that was on the failed portion from the remaining data and parity. You can create RAID-5 volumes only on dynamic disks, and you cannot mirror or extend RAID-5 volumes
RAM Random Access Memory - Primary memory in a PC. The computer can overwrite this type of memory with new data. The "random access" part of RAM derives from the way RAM stores data: The computer can locate any bit of information in RAM in an equal amount of time. This fact applies regardless of where the bit resides
raster fonts Fonts that are stored as bitmaps. Raster fonts are designed with a specific size and resolution for a specific printer and cannot be scaled or rotated. If a printer does not support raster fonts, it will not print them. The five raster fonts are Courier, MS Sans Serif, MS Serif, Small, and Symbol. aka bit-mapped fonts
raw socket A socket that provides direct access to lower-level network protocols
realm A set of security principles, in a non-Windows networked environment, that are subject to Kerberos authentication
realm name An identifying prefix or suffix appended to a user name to enable appropriate routing and authentication during a remote logon process
rebinding state A state used by DHCP clients to extend and renew their address lease when the current lease is close to expiring. In this state, the client broadcasts to the network to locate any DHCP server that can either renew or replace its currently leased configuration. The rebinding state begins when 87.5 percent of the client's lease time has elapsed
recoverable message Message Queuing: a message that can be recovered no matter which computer fails, but that uses more resources and is slower than an express message
recovery agent A person who is issued a public key certificate for the purpose of recovering user data that is encrypted with Encrypting File System (EFS)
Recovery Console A command-line interface that provides a limited set of administrative commands that are useful for repairing a PC
recovery policy

A type of public key Group Policy object used by Encrypting File System (EFS) that provides for one or more user accounts to be designated as recovery agents

Redundancy The result of establishing standby links. (Establishing standby links improves uptime by ensuring continued operation in the event that the master link fails.
refresh interval An interval of time used by secondary masters of a zone to determine how often to check if their zone data needs to be refreshed. When the refresh interval expires, the secondary master checks with its source for the zone to see if its zone data is still current or if it needs to be updated using a zone transfer. This interval is set in the SOA (start-of-authority) resource record for each zone
refresh rate The frequency with which the video screen is retraced to prevent the image from flickering. The entire image area of most monitors is refreshed approximately 60 times per second
registered file type File types that are tracked by the system registry and are recognized by the programs on the PC
registry A database repository for information about a computer's configuration. The registry contains information that Windows continually references during operation, such as:
  • Profiles for each user
  •  The programs installed on the computer and the types of documents each can create.
  • Property settings for folders and program icons.
  • What hardware exists on the system.
  • Which ports are being used.

The registry is organized hierarchically as a tree and is made up of keys and their subkeys, hives, and value entries

registry boot The default boot option used by most Windows DNS servers. When registry boot is used, DNS is started and initialized using DNS parameters and their values as they are stored in the Windows registry. You can use a Berkeley Internet Name Domain (BIND) boot file as an alternative to this method of boot configuration for DNS
relative distinguished name aka SAM account name - The part of an object's distinguished name that is an attribute of the object itself. For most objects this is the Common Name attribute. For security principals, the default common name is the security principal name
  • For the distinguished name CN=MyName,CN=Users,DC=Microsoft,DC=Com the relative distinguished name of the MyName user object is CN=MyName. The relative distinguished name of the parent object is CN=Users

relative ID master

The domain controller assigned to allocate sequences of relative IDs to each domain controller in its domain. Whenever a domain controller creates a security principal (user, group, or computer object), the domain controller assigns the object a unique security ID. The security ID consists of a domain security ID that is the same for all security IDs created in a particular domain, and a relative ID that is unique for each security ID created in the domain. At any time, there can be only one relative ID master in a particular domain

relative name

The partial DNS domain name configured in individual resource records to locate & qualify the record within a zone. The relative name is joined to the front of the parent domain (domain of origin) for each resource record to form a fully qualified domain name (FQDN) within the zone. In DNS Manager, the relative name will correspond to fields that use record-specific name properties, such as the Host computer name field used in an address (A) resource record

Remote destination A location for a DCE device that is not at the central or control site. A typical application would have a terminal at the remote site and the host computer at the central or control site.

remote access

Part of the integrated Routing and Remote Access service that provides remote networking for telecommuters, mobile workers, and system administrators who monitor and manage servers at multiple branch offices. Users with a computer running Windows and Network Connections can dial in to remotely access their networks for services such as file and printer sharing, electronic mail, scheduling, and SQL database access

remote access server

A Windows-based PC running the Routing and Remote Access service and configured to provide remote access

Remote digital loopback A test that checks the telephone link and the transmitter and receiver of a remote modem.
Remote LAN A communications networks that lies outside the geographical area of a central LAN but is connected to it through a communications network.
reservation A specific IP address within a scope permanently reserved for leased use to a specific DHCP client. Client reservations are made in the DHCP database using DHCP Manager and based on a unique client device identifier for each reserved entry
reservation Admission Control Service: an allocation of network resources, contained in a Resource Reservation Protocol (RSVP) reservation request administered by the Admission Control Service
resolver DNS client programs used to look up DNS name information. Resolvers can be either a small stub (a limited set of programming routines that provide basic query functionality) or larger programs that provide additional lookup DNS client functions, such as caching
Resource DLL A dynamic-link library (DLL) containing an implementation of the Resource application programming interface (API) for a specific type of resource. The Resource DLL is loaded into the address space of its Resource Monitor
resource domain A Windows NT 4.0 domain that is used for hosting file, print, and other application services
Resource Monitor A cluster software component that facilitates communication between a node's server cluster and one or more of its resources
resource record Standard DNS database structure containing information used to process DNS queries. eg, an address (A) type resource record contains IP address corresponding to a host name. Most of the basic resource record types are defined in RFC 1035, but additional RR types have been defined in other RFCs and approved for use with DNS
resource record set (RRset) A collection of more than one resource record returned in a query response by a DNS server. Resource record sets (RRsets) are used in responses where more than one record is part of the answer
response Windows remote access: strings expected from the device, which can contain macros
response message Message Queuing: a message sent by a receiving application to the response queue specified by a sending application. Any available queue can be specified as a response queue
response queue Message Queuing: a queue that is created by the sending application and used by the receiving application to reply to messages. eg, an application might send a response message to a response queue every time the application receives a message
retry interval The time, in seconds after the refresh interval expires, used by secondary masters of a zone to determine how often to try and retry contacting its source for zone data to see if its replicated zone data needs to be refreshed. This interval is set in the SOA (start-of-authority) resource record for each zone
reverse lookup In DNS, a query process by which the IP address of a host computer is searched to find its friendly DNS domain name. In DNS Manager, reverse lookup zones are based on the in-addr.arpa domain name and typically hold pointer (PTR) resource records
RF Radio Frequency
RFC

Request for Comments - An official document of the Internet Engineering Task Force (IETF) that specifies the details for protocols included in the TCP/IP family

RID

relative ID - The part of a security ID (SID) that uniquely identifies an account or group within a domain

RIP Routing Information Protocol - A routing protocol in TCP/IP and NetWare used to identify all attached networks as well as the number of router hops required to reach them. RIP determines the smallest hop count by communicating with other routers within the network. Only use RIP if the target router also utilizes RIP.  Novell's IPX/RIP is not compatible with the IP/RIP protocols
RIPX

Routing Information Protocol over IPX - A protocol used by routers to exchange information between routers on an IPX network and by hosts to determine the best router to use when forwarding IPX traffic to a remote IPX network

RJ-11 connector a 6-conductor modular jack typically wired for four conductors. The RJ-11 connector is most commonly known as the standard telephone jack. It is used for connecting telephone instruments, modems, and fax machines to a female RJ-11 jack on the wall or in the floor.
RJ-45 connector an 8-conductor modular jack typically wired for 8 conductors. The RJ-45 connector is most commonly known as the standard Cat5/5e/6 jack. It is used for connecting devices to a LAN using 10BaseT
roaming user profile A server-based user profile that is downloaded to the local computer when a user logs on and that is updated both locally and on the server when the user logs off. A roaming user profile is available from the server when logging on to a workstation or server computer. When logging on, the user can use the local user profile if it is more current than the copy on the server
rolling upgrade In a cluster, the process of upgrading cluster nodes by turns while the other nodes continue to provide service
ROM

read-only memory - A semiconductor circuit that contains information that cannot be modified

root

The highest or uppermost level in a hierarchically organized set of information. The root is the point from which further subsets are branched in a logical sequence that moves from a broad or general focus to narrower perspectives

root authority

The certification authority (CA) at the top of a certification hierarchy. The root CA has a self-signed certificate. aka the root certification authority

root certificate

A self-signed certification authority certificate. It is called a root certificate because it is the certificate for the root authority. The root authority must sign its own certificate because by definition there is no higher certifying authority in the certification hierarchy

root domain

The beginning of the Domain Name System (DNS) namespace. In Active Directory, the initial domain in an Active Directory tree. Also the initial domain of a forest

root hints

aka Cache hints - Local information stored on a DNS server that provides helping resource records to direct the server to its root servers. For DNS, the root hints are stored in the file Cache.dns, located in the Systemroot\System32\Dns folder

Root port Each Bridge connected to a LAN managed by the Spanning Tree Algorithm designates one of its root port. The root port connects to the root bridge

root servers

DNS servers that are authoritative for the root of the namespace

round robin

A simple mechanism used by DNS servers to share and distribute loads for network resources. Round robin is used to rotate the order of resource records (RRs) returned in a response to a query when multiple RRs of the same type exist for a queried DNS domain name

round robin

Type of Hunt Group distribution used by PBX telephone systems
Router A device that intelligently connects two or more networks [LANs or WANs] selecting the best travel path for data and directing the information accordingly.  Referring to routing tables and routing protocols, routers read the network address in each transmitted packet. Routers then decide where to send the packet. A router bases this decision on the best route. When a router port detects a packet, the router checks the routing table. The port attempts to match the network number of the destination IP address with its routing table entry. If the port finds a match, it forwards the packet to the destination network. With no match, the port forwards the packet to a router defined as the default gateway [ie to the www]
  • In a Windows environment, hardware that helps LANs and WANs achieve interoperability and connectivity, and can link LANs that have different network topologies (such as Ethernet and Token Ring). Routers match packet headers to a LAN segment and choose the best path for the packet, optimizing network performance.

  • In the Macintosh environment, routers are necessary for computers on different physical networks to communicate with each other. Routers maintain a map of the physical networks on a Macintosh internet (network) and forward data received from one physical network to other physical networks. Computers running the Server version of Windows with AppleTalk network integration can act as routers, and you can also use other routing hardware on a network with AppleTalk network integration

routing The process of forwarding a packet through an internetwork from a source host to a destination host
routing link

Message Queuing: a communications link established between Windows sites for routing messages. Specially configured Message Queuing servers with routing services enabled are used to create a routing link between sites

routing services

a service on a Message Queuing server that provides message routing services. If so configured, this feature can be used on a Message Queuing server to:

  • Enable computers that use different network protocols to communicate
  • Reduce the number of sessions by acting as a gateway for all incoming or outgoing messages for independent clients
routing-link cost Message Queuing: a number used to determine the route messages can take between two sites. This number represents the relative monetary cost of communication over a link. A routing link has a default routing-link cost of 1 and should not be changed unless you have multiple routing links between two sites and you want to enforce message routing over a specific routing link
RPC remote procedure call - A message-passing facility that allows a distributed application to call services that are available on various computers on a network. Used during remote administration of computers
RRset resource record set - A collection of more than one resource record returned in a query response by a DNS server. Resource record sets (RRsets) are used in responses where more than one record is part of the answer
RSL registry size limit - a universal maximum for registry space that prevents an application from filling the paged pool with registry data. The total amount of space that can be consumed by registry data (hives) is restricted by the registry size limit
RS-232c Adopted by the Electric Industries Association, this Recommended Standard (RS)  is a standard to specify the electrical & mechanical characteristics for connecting data equipment for serial data transmission. The letter C signifies the third in a series.
RSVP Resource Reservation Protocol - A signaling protocol that allows the sender & receiver in a communication to set up a reserved highway for data transmission with a specified quality of service
RSA A widely used public/private key algorithm. It is the default cryptographic service provider (CSP) for Microsoft Windows. It was patented by RSA Data Security, Inc. in 1977
RTS                  Request to Send - A hardware signal defined by the RS-232C standard to request permission to transmit.
RT-VBR Real Time-Variable Bit Rate - Service type that supports time-sensitive applications such as voice. Varies the rate at which cells arrive
RXD              Receiving Data - A hardware signal defined by the RS-232C standard to transport information from one device to another.

S

SACL system access control list - The part of an object's security descriptor that specifies which events are to be audited per user or group. Examples of auditing events are file access, logon attempts, and system shutdowns
SATNAV Satellite Navagation [system]: system using satellites to provide exact global position - uses GPS
SBM

subnet bandwidth management - An IETF standard that enables administrative control at the subnet level

scan interval Process Control - the time between successive checks for new processes started on the server. You can configure this in the Process Control snap-in
SCSI Small Computer System Interface: A standard high-speed, systems-level, parallel interface defined by the American National Standards Institute (ANSI). can support up to 8 devices but only uses one resource in the PC . A SCSI interface is used for connecting microcomputers to peripheral devices such as hard disks & printers, and to other computers and LANs
schema

A description of the object classes and attributes stored in Active Directory. For each object class, the schema defines the attributes an object class must have, the additional attributes it may have, and the object class that can be its parent.

The Active Directory schema can be updated dynamically. eg, an application can extend the schema with new attributes and classes and use the extensions immediately. Schema updates are accomplished by creating or modifying the schema objects stored in Active Directory. Like every object in Active Directory, schema objects have an access control list, so only authorized users may alter the schema

schema master

The domain controller assigned to control all updates to the schema within a forest. At any time, there can be only one schema master in the forest

scope A range of IP addresses that are available to be leased or assigned to DHCP clients by the DHCP service
scope of influence In a domain environment, a site, domain, or organizational unit; in a workgroup environment, the local disk
script A type of program consisting of a set of instructions to an application or tool program. A script usually expresses instructions by using the application's or tool's rules and syntax, combined with simple control structures such as loops and if/then expressions. "Batch program" is often used interchangeably with "script" in Windows
SD Card Secure Digital Card
SDP

Session Description Protocol - A protocol that TAPI uses to advertise IP multicast conferences. This protocol describes multimedia sessions for the purposes of session announcement, session invitation, and other forms of session initiation. SDP descriptors are stored in Active Directory. SDP is described in RFC 2327 of the IETF

SDRAM Synchronous DRAM

second-level domains

Domain names that are rooted hierarchically at the second tier of the domain namespace directly beneath the top-level domain names such as .com and .org. When DNS is used on the Internet, second-level domains are names such as microsoft.com that are registered and delegated to individual organizations and businesses according to their top-level classification. The organization then assumes further responsibility for parenting management and growth of its name into additional subdomains

secondary master An authoritative DNS server for a zone that is used as a source for replication of the zone to other servers. Secondary masters update their zone data only by transferring zone data from other DNS servers. They do not have the ability to perform zone updates
security descriptor A data structure that contains security information associated with a protected object. Security descriptors include information about who owns the object, who can access it and in what way, and what types of access will be audited
security group A group that can be listed in discretionary access control lists (DACLs) used to define permissions on resources and objects. A security group can also be used as an e-mail entity. Sending an e-mail message to the group sends the message to all the members of the group
security host An authentication device, supplemental to standard Windows and remote access server security, that verifies whether a caller from a remote client is authorized to connect to the remote access server
security principal An account holder that is automatically assigned a security identifier for access to resources. A security principal can be a user, group, service, or computer
security principal name A name that uniquely identifies a user, group, or computer within a single domain. This name is not guaranteed to be unique across domains
Serial communications A network in which only one data circuit is installed. The groups of eight bits are sent serially - one after another over the same wire.
SerialKey device Enables you to attach an alternate input device (also called an augmentative communication device) to your computer's serial port. This feature is designed for people who are unable to use the PC’s keyboard & mouse
Server A LAN component that provides shared resources to the network users. Servers are identified by the type of resources they provide

server cluster

A group of independent computer systems, known as nodes, working together as a single system to ensure that mission-critical applications and resources remain available to clients. A server cluster is the type of cluster that Cluster service implements

server zone

The AppleTalk zone on which a server appears. On a Phase 2 network, a server appears in the default zone of the server's default network

service

A program, routine, or process that performs a specific system function to support other programs, particularly at a low (close to the hardware) level. When services are provided over a network, they can be published in Active Directory, facilitating service-centric administration and usage. Some examples of services are the Security Accounts Manager service, File Replication service, and Routing and Remote Access service

service (SRV) resource record

A resource record used in a zone to register and locate well-known TCP/IP services. The SRV resource record is specified in RFC 2782, and it is used to locate domain controllers for Active Directory

Service Provider Interface

Calling conventions that back-end services use to make themselves accessible to front-end applications

service ticket

A ticket issued by the Kerberos V5 ticket-granting service (TGS) that allows a user to authenticate to a specific service in the domain

session

A logical connection created between two hosts to exchange data. Typically, sessions use sequencing and acknowledgments to send data reliably.

  • In load balancing TCP/IP traffic, a set of client requests directed to a server. These requests can be invoked with multiple, possibly concurrent, TCP connections. The server program sometimes maintains state information between requests. To preserve access to the server state, Network Load Balancing needs to direct all requests within a session to the same cluster host when load balancing

session concentration

For Message Queuing, a feature that typically reduces network bandwidth within a site and the number of sessions between sites. Specially configured Message Queuing servers with routing services provide session concentration

set-by-caller callback Network Connections - a form of callback in which the user supplies the telephone number that the remote access server uses for callback. This setting spares the user any long-distance telephone charges
SHA-1 Secure Hash Algorithm - A message digest hash algorithm that generates a 160-bit hash value. SHA-1 is used with the Digital Signature Algorithm (DSA) in the Digital Signature Standard (DSS), among other places
share name A name that refers to a shared resource on a server. Each shared folder on a server has a share name used by personal computer users to refer to the folder. Users of Macintosh computers use the name of the Macintosh-accessible volume that corresponds to a folder, which may be the same as the share name
shared folder permissions Permissions that restrict a shared resource's availability over the network to only certain users
SID security ID - A data structure of variable length that identifies user, group &computer accounts. Every account on a network is issued a unique SID when the account is first created. Internal processes in Windows refer to an account's SID rather than the account's user or group name
Sideband Band of frequencies adjacent to the carrier. Modulation of the carrier creates sidebands. The sidebands contain the signal data, but consume bandwidth beyond what the carrier needs. In some cases, circuitry may suppress duplicate sidebands without harming the signal data. For instance, AM becomes single sideband when circuits delete one of two identical AM sidebands. Some single sideband equipment also suppresses the carrier frequency. The carrier must then be restored at the receiver before the signal can be demodulated, that is, recovered.
SIM Subscriber Identity Module: a computer chip set in a small piece of plastic that is inserted into a GSM device - it contains the information needed to identify the user and make the GSM device [ie phone] work
Simple TCP/IP Services 4 TCP/IP services: Character Generator, Daytime Discard, Echo, and Quote of the Day

simple volume

A dynamic volume made up of disk space from a single dynamic disk. A simple volume can consist of a single region on a disk or multiple regions of the same disk that are linked together. You can extend a simple volume within the same disk or onto additional disks. If you extend a simple volume across multiple disks, it becomes a spanned volume. You can create simple volumes only on dynamic disks. Simple volumes are not fault tolerant, but you can mirror them to create mirrored volumes

single sign-on A process that allows a user with a domain account to log on to a network once, using a password or smart card, and to gain access to any computer in the domain
single switch device An assistive computer technology for people with mobility impairments. A single switch device allows users to interact with a computer by using slight body movements
SIS Single Instance Store - A component that saves disk space on the server by maintaining a single physical copy of all identical files found. If SIS finds a duplicate file on the server, it copies the original file into the SIS store and leaves a link where the original resided. This technology is used only with Remote Installation Services
site One or more well connected TCP/IP subnets. A site allows administrators to configure Active Directory access and replication topology quickly and easily to take advantage of the physical network. When users log on, Active Directory clients locate Active Directory servers in the same site as the user
SLIP Serial Line Internet Protocol - part of Windows remote access client: ensures interoperability with other remote access software
Smartphone A phone with computing capabilities, or a PDA and mobile phone in one
smart card A credit card-sized device that is used with an access code to enable certificate-based authentication and single sign-on to the enterprise. Smart cards securely store certificates, public and private keys, passwords, and other types of personal information. A smart card reader attached to the computer reads the smart card
smart card reader A PC device to read smart cards
SMB

Server Message Block - A file-sharing protocol designed to allow networked computers to transparently access files that reside on remote systems over a variety of networks. The SMB protocol defines a series of commands that pass information between computers. SMB uses four message types: session control, file, printer, and message

SME Small-to-Medium Enterprise
S/MIME Secure/Multipurpose Internet Mail Extensions - protocol for secure electronic mail over the www
SMS Short Message Service: a facility on GSM cellular systems to send short messages of up to 160 alphanumeric characters between compatible devices
SMTP             Simple Mail Transfer protocol - A member of the TCP/IP suite of protocols that governs the exchange of Email between message transfer agents [ie between PCs] usually over Ethernet, SMTP is a server-to-server protocol, so other protocols are used to access the messages
SNAP               Subnetwork Access protocol - An extension of the IEEE 802.2 LLC header used to encapsulate IP datagrams and ARP requests and replies within an 802.X (802.3, 802.4, or 802.5) frame.
snap-in A type of tool you can add to a console supported by Microsoft Management Console (MMC). A stand-alone snap-in can be added by itself; an extension snap-in can only be added to extend the function of another snap-in
SNMP              Simple Network Management Protocol - A multivendor transport layer network management protocol used to manage bridges, routers, and concentrators on TCP/IP networks. In Windows, SNMP can provide status information about a host on a TCP/IP network
SNTP Simple Network Time Protocol - protocol used to synchronize clocks over the www
SOA resource record start-of-authority resource record - A record that indicates the starting point or original point of authority for information stored in a zone. The SOA resource record (RR) is the first RR created when adding a new zone. It also contains several parameters used by other computers that use DNS to determine how long they will use information for the zone and how often updates are required
socket An identifier for a particular service on a particular node on a network. The socket consists of a node address and a port number, which identifies the service. eg, port 80 on an Internet node indicates a Web server. There are 2 kinds of sockets: streams (bidirectional) and datagrams
software decoder A type of DVD decoder that allows a DVD drive to display movies on a computer screen. A software decoder uses only software to display movies
SoHo Small Office, Home office
source journaling Message Queuing - the process of storing a copy of an outgoing message. Source journaling is configured on a message basis and is set by the sending application. When source journaling is enabled, a copy of the message is put in the source journal queue of the source computer when the message arrives at the destination (target) queue
spanned volume A dynamic volume consisting of disk space on more than one physical disk. You can increase the size of a spanned volume by extending it onto additional dynamic disks. You can create spanned volumes only on dynamic disks. Spanned volumes are not fault tolerant and cannot be mirrored
Spanning Tree-Bridging Particular algorithm or formula. Transparent bridges use the spanning tree algorithm to dynamically determine the best source-to-destination path. This algorithm avoids bridge loops (multiple paths that link one segment to another) within a network. The algorithm determines all redundant paths and makes only one of them active. The spanning tree protocol (STP) is part of IEEE standard 802.1.
special access permissions On NTFS volumes, a custom set of permissions. You can customize permissions on files and directories by selecting the individual components of the standard sets of permissions
SPID

Service Profile Identifier - An 8-digit to 14-digit number that identifies the services that you ordered for each B-channel. eg, when you order Primary Rate ISDN, you obtain two phone numbers and two SPIDs from your ISDN provider. Typical ISDN adapters cannot operate without configuring SPIDs

Splitter An ADSL device that accommodates analog telephones, plus digital data access over the Internet. With a splitter, analog voice signals transmit at baseband frequencies. These combine with passband data transmission through a low-pass filter.
SSL Secure Sockets Layer -  proposed open standard for establishing a secure communications channel to prevent the interception of critical information, such as credit card numbers. Primarily, it enables secure electronic financial transactions on the www, although it is designed to also work on other Internet services
Start Application Enable When checked, the server DDE application automatically starts when a client DDE application attempts to initiate a DDE conversation. When cleared, attempts to open a DDE conversation succeed only if the server DDE application is already running
static dialog box A scripted dialog box between the client computer and an intermediary device:  requires no response from the user
Static route

Permanent routes in the routing table that the router stores. An entry manually configured by a network administrator defined in a routing table that never changes or expires. A static route entry will contain the target address, the next hop router address on the way to that target, and a value assigned to the entry indicating how it rates compared to other router to the same target If the routing protocol is configured to support auto-static routes (automatically added static routes), then the router can issue a request to a protocol to get an update of routing information on a specific interface. The results of such an update are then converted and kept as static routes

STP                Spanning Tree protocol - An algorithm specified in the IEEE 802.3 standard to manage multiple links within a LAN. The Spanning Tree Algorithm allows the use of redundant links within the same network without creating active loops
strict RFC checking a form of domain name checking that examines characters used in DNS names for compliance with DNS naming requirements and valid character usage as specified in RFC 1123, Requirements for Internet Hosts - Applications and Support. For strict RFC compliance, DNS domain names will use name labels made up only of valid uppercase and lowercase letters, number characters, and hyphens (A through Z, a through z, 0 through 9, -), separated by periods
string A group of characters or character bytes handled as a single entity. Computer programs use strings to store and transmit data and commands. Most programming languages consider strings (such as 2674:gstmn) as distinct from numeric values (such as 470924)
subkey A key within a key. In the registry structure, subkeys are subordinate to subtrees and keys. Keys and subkeys are similar to the section header in .ini files; however, subkeys can carry out functions
subnet

A subdivision of an IP network. Each subnet has its own unique subnetted network ID

Subnet address An extension of the IP addressing scheme that allows a site to use a single IP address for multiple physical addresses. Outside of the site, routing continues as usual by dividing the destination address into an Internet portion and a local portion. Gateways and hosts inside the site interpret the local portion of the address by dividing it into a physical network portion and a host portion
Subnet mask A 32-bit value that enables the recipient of IP packets to distinguish the network ID and host ID portions of the IP address. Typically, subnet masks use the format 255.x.x.x. This mask is referred to as the subnet mask because the network portion of the address can be determined by the class inherent to an IP address. The subnet mask has 1s in positions corresponding to the network and subnet numbers and Os in the host number positions

 Subnet masks split one network into a set of mini networks or subnets. Subnetting helps to reduce traffic on each subnet. Subnetting also makes the network more manageable. Each subnet functions as if it were an independent network

subtree

Any node within a tree, along with any selection of connected descendant nodes. In the registry structure, subtrees are the primary nodes that contain keys, subkeys, and value entries

SVC Switched Virtual Circuit - A frame relay and ATM networking term: Virtual connection between two variable endpoints on the network. The switch makes at the beginning of the call, and breaks at the end of the call
SVGA Super Video Graphs Array: the term given to video cards which can display a varying range of resolutions with different numbers of colours - the user can also adjust the refresh rate of the screen via the card settings to eliminate screen flicker
switch type The type of interface to which an ISDN device is attached. aka Switch
switching hub A central network device (multiport hub) that forwards packets to specific ports rather than, as in conventional hubs, broadcasting every packet to every port. In this way, the connections between ports deliver the full bandwidth available
symmetric encryption An encryption algorithm that requires the same secret key to be used for both encryption and decryption. Because of its speed, symmetric encryption is typically used when a message sender needs to encrypt large amounts of data. aka secret key encryption
SyncML Synchronisation Markup language
system area network A network configuration, usually on a separate Internet Protocol (IP) subnet, that gives data a direct path to system hardware

system files

Files used by Windows to load, configure, and run the operating system. Generally, system files must never be deleted or moved

system partition

The partition that contains the hardware-specific files needed to load Windows (ie, Ntldr, Osloader, Boot.ini, Ntdetect.com). The system partition can be, but does not have to be, the same as the boot partition

System Policy

A Windows NT 4.0-style policy based on registry settings made using Poledit.exe, the System Policy Editor

system queue

For Message Queuing, a queue that stores various types of administrative messages. Message Queuing uses up to five system queues, all of which are private queues. System queues cannot be deleted

System Restore

A tool that tracks changes to your computer and creates a restore point when it detects the beginning of a change. You can use the System Restore Wizard to select a restore point to restore your computer to an earlier state when your computer was functioning the way you like

system volume

The volume that contains the hardware-specific files that are needed to load Windows on x86-based computers with a BIOS. The system volume can be, but does not have to be, the same volume as the boot volume

systemroot

The path and folder name where the Windows system files are located. eg, C:\Windows

SYSVOL

A shared directory that stores the server copy of the domain's public files, which are replicated among all domain controllers in the domain

T

T1 A digital carrier facility used to transmit a DS-1 formatted digital signal at 1.544 Mbps.
tag Indexing Service - one or more terms that identify an element in a query, such as weight, phrase, property, or regular expression. eg, the tag {prop name=created} specifies the Created property in a query
TAPI

Telephony application programming interface - used by communications programs to work with telephony and network services. Communications programs like HyperTerminal and Phone Dialer use TAPI to dial, answer, and route telephone calls on conventional telephony devices, including PBXs, modems, and fax machines. TAPI 3.0 also provides Internet Protocol (IP) telephony support, which Phone Dialer and other programs use to transmit, route, and control real-time audio and video signals over IP-based networks such as the www

target The mapping destination of a DFS root or link, which corresponds to a physical folder that has been shared on the network
TCP/IP Transmission Control Protocol/Internet Protocol - protocol used by networked computers to communicate - A connection-oriented protocol that provides transport facilities, standards & conventions to processors on a single or multiple network environment
TDI

Transport Driver Interface - A common set of routines for network layer components that communicate with the session layer of the Open Systems Interconnection (OSI) model. These routines allow software components above & below the transport layer to be mixed and matched without reprogramming

Telnet A terminal-emulation protocol that is widely used on the Internet to log on to network computers. Telnet also refers to the application that uses the Telnet protocol for users who log on from remote locations
Telnet            Teletype network An Internet standard protocol for remote terminal connection service that allows a user to interact with a system at another site as if the terminal were connected directly to the remote machine
terminal A device consisting of a display screen and a keyboard that is used to communicate with a PC
terminal telecomms - a dedicated system proprietary digital telephone
Terminal emulation A type of software that allows a computer connected to a piece of equipment to appear to be a traditional terminal with a standard interface - often a DEC VT100 (asynchronous) terminal
ticket A set of identification data for a security principle, issued by a domain controller for purposes of user authentication. Two forms of tickets in Windows are ticket-granting tickets (TGTs) and service tickets
TFTP              Trivial File Transfer Protocol - A simple TCP/IP file transfer protocol used for downloading boot code to diskless workstations
TFT Thin Film Transistor - the active matrix LCD panel which offers the highest quality display for portable PCs - TFT can display 16 million colours at high resolutions
TGS ticket-granting service - A Kerberos V5 service provided by the Kerberos V5 Key Distribution Center (KDC) service that issues service tickets that allow users to authenticate to services in a domain
TGT ticket-granting ticket - A credential issued to a user by the Kerberos Key Distribution Center (KDC) when the user logs on. The user must present the TGT to the KDC when requesting session tickets for services. Because a TGT is normally valid for the life of the user's logon session, aka user ticket
Throughput The end result of a data call. Throughput also refers to the actual amount of useful and non-redundant information that is transmitted or processed
time slice aka quantum - A period of time during which a particular task is given control of the microprocessor in a time-sharing multitasking environment. A computer's processor is allocated to an application, usually measured in milliseconds
time server A computer that periodically synchronizes the time on all computers within a network

time stamp

A certification by a trusted 3rd party specifying that a particular message existed at a specific time & date. 3rd parties generate a trusted time stamp for a given message by having a time stamping service add a time value to a message and then digitally sign

TLS

Transport Layer Security - A standard protocol that is used to provide secure Web communications on the Internet or intranets. It enables clients to authenticate servers or, optionally, servers to authenticate clients. It also provides a secure channel by encrypting communications. TLS is the latest and a more secure version of the SSL protocol

Toggle Button/Key A feature activated by pressing a button [key] that alternates each time [ie night mode on/off key]
token Any nonreducible textual element in data that is being parsed. eg the use in a program of a variable name, a reserved word, or an operator. Storing tokens as short codes shortens program files and speeds execution
token networking: a unique structured data object or message that circulates continuously among the nodes of a token ring and describes the current state of the network. Before any node can send a message on the network, it must first wait to control the token
top-level domains Domain names that are rooted hierarchically at the first tier of the domain namespace directly beneath the root (.) of the DNS namespace. On the www, top-level domain names such as .com and .org are used to classify and assign second-level domain names (such as microsoft.com) to individual organizations and businesses according to their organizational purpose
Topology The layout of nodes and links that constitute a LAN. It is a geometric physical or electrical configuration that describes a local communication network. The most common distribution system topologies are the bus, ring, and star
touch-tone dialing aka DTMF aka MF - A form of dialing that uses multi-tone signalling. The user hears a series of tones  when dialing. Push-button telephones usually use touch-tone dialing
trace log a log generated when the user selects a trace data provider using Performance. Trace logs differ from counter-data logs in that they measure data continuously rather than take periodic samples
transaction Message Queuing: the pairing of two or more actions that are performed together as a single action; the action succeeds or fails as a whole. Using Microsoft Distributed Transaction Coordinator (MS DTC) ensures that either both actions succeed or neither is executed
transaction dead-letter queue Message Queuing: a queue that stores transactional messages that cannot reach their destination queue. Transaction dead-letter queues store failed messages on the computer on which the message expired. Messages in these queues are written to disk and are recoverable
transactional message For Message Queuing, a message that can be sent and received only from within a transaction. This type of message returns to its prior state when a transaction is terminated abruptly. A transactional message is removed from a queue only when the transaction is committed; otherwise, it remains in the queue and can be subsequently read during another transaction
transceiver A device that can both transmit and receive signals. On LANs, a transceiver is the device that connects a PC to the network and that converts signals to and from parallel and serial form
transitive trust The standard type of trust relationship between Windows domains in a domain tree or forest. When a domain joins an existing forest or domain tree, a transitive trust is automatically established. Transitive trusts are always two-way relationships. This series of trusts, between parent and child domains in a domain tree and between root domains of domain trees in a forest, allows all domains in a forest to trust each other for the purposes of authentication. eg, if domain A trusts domain B and domain B trusts domain C, then domain A trusts domain C
Transparent bridging A bridging protocol in which the bridge learns the addresses and location of the network devices (the PCs) while those devices remain unaware of the presence of the bridge.

transport provider

The driver and support files that provide transport services in a networking environment

trap

In Simple Network Management Protocol (SNMP), a message sent by an agent to a management system indicating that an event has occurred on the host running the agent

Tri-band Specific to handsets, a tri-band cellular phone will operate on three different frequencies, depending on the available network
TFTP Trivial File Transfer Protocol - protocol used to download the initial files needed to start the installation
TTL Time to Live - A timer value included in packets sent over TCP/IP-based networks that tells the recipients how long to hold or use the packet or any of its included data before expiring and discarding the packet or data. For DNS, TTL values are used in resource records within a zone to determine how long requesting clients should cache and use this information when it appears in a query response answered by a DNS server for the zone.
trust relationship A logical relationship established between domains to allow pass-through authentication, in which a trusting domain honours the logon authentications of a trusted domain. User accounts and global groups defined in a trusted domain can be given rights and permissions in a trusting domain, even though the user accounts or groups don't exist in the trusting domain's directory
TSID transmitting station ID string - A string that specifies the transmitter subscriber ID sent by the fax machine when sending a fax to a receiving machine. This string is usually a combination of the fax or telephone number and the name of the business
TSR terminate-and-stay-resident program - A program running under MS-DOS that remains loaded in memory even when it is not running, so that it can be quickly invoked for a specific task performed while any other application is operating
tunnel

A logical connection over which data is encapsulated. Typically, both encapsulation and encryption are performed and the tunnel is a private, secure link between a remote user or host and a private network

tunnel server

A server or router that terminates tunnels and forwards traffic to the hosts on the target network

Twisted-pair wire A pair insulated copper conductors that are twisted around each other to cancel the effects of electrical noise. Twisted-pair wiring is typical of standard telephone wiring. ie cw1308 standard

two-way trust

 

A type of trust relationship in which both of the domains in the relationship trust each other. In a two-way trust relationship, each domain has established a one-way trust with the other domain. eg, domain A trusts domain B and domain B trusts domain A. Two-way trusts can be transitive or nontransitive. All two-way trusts between Windows domains in the same domain tree or forest are transitive

U

UART            Universal Asynchronous Receiver/Transmitter - an integrated circuit used for serial communications, containing a transmitter (parallel-to-serial converter) and a receiver (serial-to-parallel converter)
UBR Unspecified Bit Rate - Best effort service that does not require tightly constrained delay and delay variation. UBR provides no specific quality of service or guaranteed throughput
UCS Unicode Character System - An international standard character set reference that is part of the Unicode standard. The most widely held existing version of the UCS standard is UCS-2, which specifies 16-bit character values currently accepted and recognized for use to encode most of the world's languages
UDP User datagram protocol - A series of internet standard network layer, transport layer, and session layer protocols that provide simple but unreliable datagram services. When reliable delivery is unnecessary, communications may use UDP instead of TCP
UDP socket

A socket that transmits datagrams over the User Datagram Protocol

UTF-8

Unicode Transmission Format 8 - A character set for protocols evolving beyond the use of ASCII. The UTF-8 protocol provides for support of extended ASCII characters and translation of UCS-2, an international 16-bit Unicode character set. UTF-8 enables a far greater range of names than can be achieved using ASCII or extended ASCII encoding for character data

UMTS (3G) Universal Mobile Telecommunications Services
UNC

Universal Naming Convention - A convention for naming files and other resources beginning with two backslashes (\), indicating that the resource exists on a network computer. UNC names conform to the \\SERVERNAME\SHARENAME syntax, where SERVERNAME is the server's name and SHARENAME is the name of the shared resource. The UNC name of a directory or file can also include the directory path after the share name, with the following syntax: \\SERVERNAME\SHARENAME\DIRECTORY\FILENAME

UNC name Universal Naming Convention name - the full name of a resource on a network. It conforms to the \\servername\sharename syntax, where servername is the name of the server and sharename is the name of the shared resource. UNC names of directories or files can also include the directory path under the share name, with the following syntax:
\\servername\sharename\directory\filename
unicast to transmit data from one terminal to another, eg from client to server, or from server to server
Unicode A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode character repertoire has multiple representation forms, including UTF-8, UTF-16, and UTF-32. Most Windows interfaces use the UTF-16 form
Unique bridge identifier An identifier derived from the bridge address and the manageable priority assigned to the bridges. The relative priority of the bridge in the LAN is determined by the comparison of the unique identifiers. The lower the numerical value, the higher the priority

universal group

A security or distribution group that can be used anywhere in the domain tree or forest. A universal group can have members from any Windows domain in the domain tree or forest. It can also include other universal groups, global groups, and accounts from any domain in the domain tree or forest. Rights and permissions must be assigned on a per-domain basis, but can be assigned at any domain in the domain tree or forest.

Universal groups can be members of domain local groups and other universal groups, but they cannot be members of global groups. Universal groups appear in the global catalog and should contain primarily global groups

UNIX

A powerful, multiuser, multitasking operating system initially developed at AT&T Bell Laboratories in 1969 for use on minicomputers. UNIX is considered more portable, that is, less computer-specific, than other operating systems because it is written in C language. Newer versions of UNIX have been developed at the University of California at Berkeley and by AT&T

UPN suffix user principal name suffix - the part of the user principal name to the right of the @ character. The default UPN suffix for a user account is the DNS domain name of the domain that contains the user account. Alternative UPN suffixes may be added to simplify administration and user logon processes by providing a single UPN suffix for all users. The UPN suffix is only used within the Active Directory forest and is not required to be a valid DNS domain name
UPS uninterruptible power supply - battery powered equipment connected between a device [eg PC] and mains power that ensures electrical power remains in the event of mains failure. UPS devices also offer mains stability features
URL

Uniform Resource Locator - An address that uniquely identifies a location on the www. aka Internet address: An address for a resource on the Internet that is used by Web browsers to locate Internet resources. An Internet address typically starts with a protocol name, followed by the name of the organization that maintains the site; the suffix identifies the kind of organization it is. eg, the address http://www.sjgl.co.uk/ provides the following information:

http: Web server uses the Hypertext Transfer Protocol.

www: site is on the World Wide Web.

.co.uk: This is a UK based company

USB Universal Serial Bus: allows up to 127 different devices to be connected to one port on the computer by utilising hubs - all the devices connected via the USB use only the one resource in the PC. Supports data transfer rates of 12 Mbps
USER object An object from Window Manager, which includes windows, menus, cursors, icons, hooks, accelerators, monitors, keyboard layouts, and other internal objects

user profile

A file that contains configuration information for a specific user, such as desktop settings, persistent network connections, and application settings. Each user's preferences are saved to a user profile that Windows uses to configure the desktop each time a user logs on

user rights

Tasks that a user is permitted to perform on a computer system or domain. There are two types of user rights: privileges and logon. An example of a privilege is the right to shut down the system. An example of a logon right is the right to log on to a computer locally. Both types are assigned by administrators to individual users or groups as part of the security settings for the PC

Users

A special group that contains all users who have user permissions on the server

USP Unique Selling Point

V

V.25 bis An automatic calling & answering protocol and command set for modems that need auto-dial capabilities
V34 Data transmission standard up to 33,600bps over phone lines. It defines a full-duplex (2-way) modulation technique and includes error-correcting & negotiation
V.90 Data transmission standard up to 56,000bps [56k] over phone lines. The transmission speed from the client-side modem is 33,600 bps, the same as V.34. The tx speed from the host-side modem is up to 56,000 bps, with a mean speed of 40,000 to 50,000 bps
VCI Virtual Channel Identifier - Address of a virtual circuit. An integer that ranges from 0 to 65,535. The integer identifies a virtual channel that cells may traverse
VGA

Video Graphics Array

vector

an ordered series of words or numbers used in an index query

Video Frame a frame of video = one image in a video sequence

virtual address

in a virtual memory system, the address the application uses to reference memory. The kernel and the memory management unit (MMU) translate this address into a physical address before the memory is read or written
virtual container A container that allows any LDAP-compliant directory to be accessed through Active Directory
virtual IP address An IP address that is shared among the hosts of a Network Load Balancing cluster. A Network Load Balancing cluster might also use multiple virtual IP addresses, ie, in a cluster of multihomed Web servers
virtual memory Temporary storage used by a computer to run programs that need more memory than it has. eg, programs could have access to 4 gigaby