B8ZS

Binary 8-Zero Substitution.

B-Tree Format

The format used for indexes in SQL Server. B-Tree is short for balanced tree. It is called this because every page of the index is exactly the same distance from the root as is every other page at the same level. A B-Tree resembles a pyramid.

Backbone

Connects all OSPF areas allowing any router in the AS (area) to connect to any other AS; this can be accomplished with tunnels.

Back Door

A feature programmers often build into programs to allow special privileges normally denied to users of the program. Often programmers build back doors so they can fix bugs. If hackers or others learn about a back door, the feature may pose a security risk. Also known as a trapdoor.

Back End

The server component of a client/server system. It provides services to the front end (the client component).

Back-End Program

A server application that provides services to front-end programs (client applications). Exchange Server is an example of a back-end program. See also Front-End Program.

BackOffice

Microsoft’s line of client/server support applications that run on Windows NT Server. Some components of BackOffice are Microsoft SQL Server, Systems Management Server (SMS), Internet Information Server (IIS), Exchange Server, SNA Server, and Proxy Server.

Back Orifice

Back Orifice is a program developed and released by The Cult of the Dead Cow (cDc). It is not a virus; it is a remote administration tool with potential for malicious misuse. If installed by a hacker, it has the ability to give a remote attacker full system administration privileges to your system. It can also “sniff” passwords and confidential data and quietly e-mail them to a remote site. Back Orifice is an extensible program – programmers can change and enhance it over time. See also Password Sniffing.

Background Task

A task executed by the system but generally remain invisible to the user. The system usually assigns background tasks a lower priority than foreground tasks. Some malicious software is executed by a system as a background task so the user does not realize unwanted actions are occurring.

Backup

The process of writing all the data contained in online mass storage devices to offline mass storage devices for the purpose of safe keeping. Backups are usually performed from hard disk drives to tape drives. Also referred to as archiving. See also Hard Disk Drive.

Backup Browser

A computer on a Microsoft network that maintains a list of computers and services available on the network. The Master Browser supplies this list. The backup browser distributes the Browsing service load to a workgroup or domain. See also Master Browser.

Backup, Copy

A backup operation in which files are backed up but are not marked as having been backed up. A copy backup is often made for archival or redundancy purposes.

Backup, Daily

A backup operation in which all of the files that have changed on a certain day are backed up.

Backup Device

A file or tape to which SQL Server backs up a database. Also called a dump device. SQL has no built-in backup devices that point to files or tapes. You will need to create all your backup devices that point to files or tapes.

Backup, Differential

A backup operation in which all files that are marked as not having been backed up are copied. The files are not marked as having been backed up. In most backup plans, a differential backup includes all of the files that have changed since the last full backup.

Backup Domain Controller (BDC)

The Backup Domain Controller’s user account database is a replicated copy of that from the Primary Domain Controller (PDC). See also Primary Domain Controller.

Backup, Incremental

A backup operation in which all files that are marked as not having been backed up are copied. The files are marked as having been backed up. In most backup plans, an incremental backup includes all of the files that have changed since the last full or incremental backup.

Backup, Normal

A backup operation in which all of the files in a file system location are backed up and are marked as having been marked up.

Backup Operators Group

A Windows 2000 built-in group that includes users who can back up and restore the file system, even if the file system is NTFS and they have not been assigned permissions to the file system. The members of the Backup Operators group can only access the file system through the Windows 2000 Backup utility. To be able to directly access the file system, the user must have explicit permissions assigned.

Backup Type

A backup choice that determines which files are backed up during a backup process. Backup types include normal backup, copy backup, incremental backup, differential backup, and daily backup.

Backup Utility

The Windows Server 2003 utility used to run the Backup Wizard, the Restore Wizard, and the Automated System Recovery Wizard.

Backup Wizard

A Wizard that is used to perform backup operations. The Backup Wizard is accessed through the Backup utility.

Backward Explicit Congestion Notification (BECN)

BECN is the bit set by a Frame Relay network in frames moving away from frames headed into a congested path. A DTE that receives frames with the BECN may ask higher-level protocols to take necessary flow control measures.

Bandwidth

In network communications, the amount of data that can be sent across a wire in a given time. Each communication that passes along the wire decreases the amount of available bandwidth.

Bandwidth Allocation Protocol (BAP)

A PPP option for multilink connections to control the amount of bandwidth used by connections to RAS servers. See also Point-to-Point Protocol, Multilink, Bandwidth, and Remote Access Service.

Bandwidth Priorities

The relative amount of available bandwidth you assign to a particular type of external traffic.

Bandwidth Throttling

A technology that allows you to limit how much network bandwidth can be used by a given website. It prevents a particular website from hogging bandwidth and adversely affecting the performance of the other sites on the web server. See also Bandwidth.

Base64

An encoding scheme used by MIME-compliant mail systems to convert binary files into a text format that can be processed and sent as e-mail. See also Binary File and Multipurpose Internet Mail Extension.

Baseband

The entire bandwidth is used by a signal. Found in digital communication.

Base I/O Port Address

Defines a memory address through which data will flow to and from the adapter.

Baseline

A snapshot of your computer’s current performance statistics that can be used for analysis and planning purposes.

Base Memory

The first 1 MB of random access memory (RAM).

Base Memory Address

A place in the computer’s memory that marks the beginning of a buffer area reserved for the network adapter.

BASIC

A high level programming language. The name stands for Beginner’s All-purpose Symbolic Instruction Code.

Basic Input/Output System (BIOS)

A set of routines in firmware that provides the most basic software interface drivers for hardware attached to a computer. The BIOS contains the bootstrap routine. See also Boot, Driver and Firmware.

Basic Management Setup

Used with Cisco routers when in setup mode. Only provides enough management and configuration to get the router working so someone can telnet into the router and configure it.

Basic Rate ISDN (BRI)

Basic Rate ISDN uses three channels. Two channels (called B channels) carry the digital data at 64 Kbps. A third channel (called the D channel) provides link and signaling information at 16 Kbps. Basic Rate ISDN thus is referred to as 2B+D. A single PC transmitting through ISDN can use both B channels simultaneously, providing a maximum data rate of 128 Kbps (or higher with compression).

Basic Storage

A disk-storage system supported by Windows 2000 that consists of primary partitions and extended partitions. See also Extended Partition and Primary Partition.

Bastion Host

The computer system that sits at the edge of a private network and guards against external threats.

Batch File

An ASCII formatted file that contains MS-DOS commands which can be executed by the computer.

Batch Group

A Windows 2000 special group that includes users who log on as a user account that is only used to run a batch job.

Batch Program

An ASCII file that contains one or more Windows NT commands. A batch program’s filename typically has a .bat or .cmd extension. When you type the filename at the command prompt, the commands are processed sequentially.

Baud

Synonymous with bits per second (bps), if each signal element represents one bit. It is a unit of signaling speed equivalent to the number of separate signal elements transmitted per second.

Baud Rate

The per-second rate of state transitions (that is, from 1 to 0 and vice versa) of a signal. Baud rates of modems define the speed at which they make state transitions. Because state transitions can represent more than a single bit each, this rate is different from the BPS rate.

BBS

Acronym for “Bulletin Board System”.

BCD

Acronym for “Binary Code Decimal”.

B Channel

A full-duplex, 64Kbps channel in ISDN that transmits user data. Also known as a bearer channel.

BCP (Bulk Copy Program)

A command-line utility used for transferring information into and out of SQL Server.

BDC

Acronym for “Backup Domain Controller”.

Beacon

An FDDI device or Token Ring frame that points to a serious problem with the ring, such as a broken cable. The beacon frame carries the address of the station thought to be down. See also Failure Domain.

Beaconing

The process of a Token Ring network by which a device, in the event of a cable fault, determines the state of the network and the location of the fault.

BECN

See Backward Explicit Congestion Notification.

Benchmark Program

A program that attempts to provide a consistent measurement of system performance. Here are some examples:

• Dhrystone, which measures microprocessor and memory performance.

• Whetstone, which measures speed of arithmetic operations.

• Khornerstone, which measures overall system performance, including disk-drive access speed, memory access speed, and processor performance.

The Systems Performance Evaluation Cooperative (SPEC) developed a set of ten tests to measure performance in actual application environments. The results of these tests are known as SPECmarks.

Berkeley Internet Name Daemon (BIND)

The Unix standard for DNS. Windows Server 2003 is compliant with several versions of BIND (specifically, BIND 4.9.7, 8.1.2, 8.2, and 9.1.0). Active Directory requires DNS and BIND version 8.1.2. BIND versions prior to 4.9.4 don’t support compression, and they can receive only one Resource Record at a time. If your secondary servers are running older versions of BIND, then you will need to disable these features.

Berkeley Software Distribution Unix

Abbreviated BSD Unix, and also known as Berkeley Unix. BSD Unix was developed at the University of California at Berkeley by researchers working in the Computer Systems Research Group (CSRG) from the 1970s to 1993 when the group finally closed its doors. BSD added many significant advanced features to Unix, including the C shell, the vi editor, TCP/IP networking additions, and virtual memory. Because the CSRG was an academic group producing state-of-the-art software with no support obligations, BSD Unix was not supported in the normal way; bug fixes were sometimes made available, but it was a hit-and-miss process at best. For this reason, BSD Unix appealed to the research community and scientific users rather than to commercial users who tended to use Unix from AT&T. BSD Unix 4.1 through to the last release, version 4.4, and the related commercial products, including those from Sun Microsystems, DEC, and Mt Xinu, are still popular and in use in universities and commercial institutions all over the world. See also FreeBSD, Linux, NetBSD, and Unix.

Berkeley Unix

See Berkeley Software Distribution Unix.

BGP4

See BGP Version 4.

BGP Version 4

Version 4 of the interdomain routing protocol most commonly used on the Internet. BGP4 supports CIDR and uses route-counting mechanisms to decrease the size of routing tables. See also Classless Interdomain Routing.

Bidirectional Trusts

See Two-Way Trust.

Bimodal Virus

A bimodal virus infects both boot records and files. Also known as Bipartite. See also Boot Sector Infector, File Viruses and Multipartite Virus.

Binary

The numbering system used in computer memory and in digital communication. All characters are represented as a series of 1s and 0s. For example, the letter A might be represented as 01000001.

Binary 8-Zero Substitution (B8ZS)

A line-code type, interpreted at the remote end of the connection, that uses a special code substitution whenever eight consecutive zeros are transmitted over the link on T1 and E1 circuits. This technique assures ones density independent of the data stream. Also known as bipolar 8-zero substitution. See also
Ones Density.

Binary File

A file consisting of binary information. Usually, a binary file is a program or a data file in machine-readable form rather than in human-readable ASCII text. You can converrt a binary file into a text-based form so that you can transmit it over the Internet. See also Base64 and Multipurpose Internet Mail Extension.

Bindery

An administrative model that is used by Novell NetWare versions up to NetWare 3.2 (All Novell servers that are version 4 or higher use directory services). It is analogous to the Registry in Windows NT. See also
Registry.

Binding

A process that establishes the initial communication channel between the protocol driver and the network adapter card driver. See also Network Layer and Data Link Layer.

BIOS

See Basic Input/Output System.

BIP

See Bit Interleaved Parity.

BISDN

See Broadband ISDN.

Bit

A binary digit; the smallest unit of information that can be stored, either as 1 or as 0. See also Byte.

Bit Interleaved Parity (BIP)

A method used in ATM to monitor errors on a link, sending a check bit or word in the link overhead for the previous block or frame. This allows bit errors in transmissions to be found and delivered as maintenance information.

Bitmap

A technique for managing the image displayed on a computer screen.

Bit-Oriented Protocol

Regardless of frame content, the class of Data-Link layer communication protocols that transmits frames. Bit-oriented protocols, as compared with byte-oriented, supply more efficient and trustworthy, full-duplex operation.

Bits per Second (BPS)

The amount of data transferred in a second.

Block Interleaving

A process that involves distributing the data block-by-block across the disk array in the same location across each disk. This is used by RAID 0.

BNC

Acronym for “Bayonet Nut Connector” (British Naval Connector).

Boot

The process of loading a computer’s operating system. Booting usually occurs in multiple phases, each successively more complex until the entire operating system and all its services are running. Also called bootstrap. The computer’s BIOS must contain the first level of booting. See also Basic Input/Output System.

Boot Information Negotiation Layer (BINL)

A portion of Remote Installation Services (RIS) that allows for connecting clients to a RIS server. See also Remote Installation Services (RIS).

Booting Up

The process of starting up the computer.

BOOT.INI

A file accessed during the Windows 2000 boot sequence. The BOOT.INI file is used to build the operating system menu choices that are displayed during the boot process. It is also used to specify the location of the boot partition.

Boot Normally

A Windows 2000 Advanced Options menu item used to boot Windows 2000 normally.

BOOTP

See Bootstrap Protocol.

Boot Partition

The volume, formatted for either an NTFS, FAT, or HPFS file system, that contains the Windows NT operating system’s files. Windows NT automatically creates the correct configuration and checks this information whenever you start your system. See also Partition and System Partition.

Boot PROM

Boot PROM allows the network card to boot up and connect over the network, as the Boot PROM has the necessary connection software to use.

Boot Record

The program recorded in the boot sector. This record contains information on the characteristics and contents of the disk and information needed to boot the computer. If a user uses a PC with a floppy disk, the system reads the boot record from that disk. See also Boot Sector.

Boot ROM

Used in routers to put the router into bootstrap mode. Bootstrap mode then boots the device with an operating system. The ROM can also hold a small Cisco IOS.

BOOTSECT.DOS

An optional file that is loaded if the user chooses to load an operating system other than Windows 2000. This file is only used in dual-boot or multi-boot computers.

Boot Sector

An area located on the first track of floppy disks and logical disks that contain the boot record. Boot sector usually refers to this specific sector of a floppy disk, whereas the term Master Boot Record usually refers to the same section of a hard disk. See also Master Boot Record.

Boot Sector Infector

A boot sector infector virus places its starting code in the boot sector. When the computer tries to read and execute the program in the boot sector, the virus goes into memory where it can gain control over basic computer operations. From memory, a boot sector infector can spread to other drives (floppy, network, etc.) on the system. Once the virus is running, it usually executes the normal boot program, which it stores elsewhere on the disk. Also known as Boot Virus, Boot Sector Virus and BSI.

Bootstrap Protocol (BOOTP)

Predecessor to the DHCP protocol. BOOTP was used to assign IP addresses to diskless workstations. See also Dynamic Host Configuration Protocol.

Border Gateway

A router that facilitates communication with routers in different autonomous systems.

Border Routing

The passing of packets from one internetwork to another.

Bottleneck

A condition in which network data transfer is slowed significantly because of a problem with a network device.

Bounded Media

A physical form of media, such as a cable.

Boundless Media

A wireless form of media, such as radio waves.

BPB

Acronym for “BIOS Parameter Block”.

BPDU

See Bridge Protocol Data Unit.

Branching

Transferring execution of commands to another part of batch file.

Branch Office

A wholly controlled facility that does not meet the criteria to be a corporate office.

BREAK

Sets or clears extended CTRL+C checking.

BRI

See Basic Rate ISDN.

Bridge

A device for connecting two segments of a network and transmitting packets between them. Both segments must use identical protocols to communicate. Bridges function at the Data Link layer, Layer 2 of the OSI reference model. The purpose of a bridge is to filter, send, or flood any incoming frame, based on the MAC address of that particular frame. See also Router and Data Link Layer.

Bridgehead Server

A nominated server that acts as a message transfer point between Exchange 2000 routing groups. This term can also refer to the computer hosting a directory replication connector.

Bridge Protocol Data Unit (BPDU)

A Spanning-Tree Protocol initializing packet that is sent at definable intervals for the purpose of exchanging information among bridges in networks.

Broadband

A transmission methodology for multiplexing several independent signals onto one cable. In telecommunications, broadband is classified as any channel with bandwidth greater than 4kHz (typical voice grade). In LAN terminology, it is classified as coaxial cable on which analog signaling is employed. Also known as wideband.

Broadband ISDN (BISDN)

ITU-T standards created to manage high-bandwidth technologies such as video. BISDN presently employs ATM technology along SONET-based transmission circuits, supplying data rates between 155Mbps and 622Mbps and beyond. See also Basic Rate ISDN, Integrated Services Digital Network, and Primary Rate ISDN.

Broadband Network

A technique for transmitting a large amount of information, including voice, data, and video, over long distances using the same communications channel. Sometimes called wideband transmission, it is based on the same technology used by cable television.

Broadcast

A data frame or packet that is transmitted to every node on the local network segment (as defined by the broadcast domain). Broadcasts are known by their broadcast address, which is a destination network and host address with all the bits turned on. Also called “local broadcast.”

Broadcast and Unknown Servers

In LAN emulation, the hardware or software responsible for resolving all broadcasts and packets with unknown (unregistered) addresses into the point-to-point virtual circuits required by ATM. See also LAN Emulation, LAN Emulation Client, LAN Emulation Configuration Server, and LAN Emulation Server.

Broadcast Domain

A group of devices receiving broadcast frames initiating from any device within the group. Because they do not forward broadcast frames, broadcast domains are generally surrounded by routers.

Broadcast Packet

A network packet that is addressed in a manner that identifies its destination as being all computers.

Broadcast Storm

A sudden flood of broadcast messages that clogs the transmission medium, approaching use of 100 percent of the bandwidth. Broadcast storms cause performance to decline and, in the worst case, computers cannot even access the network.

Broken Ownership Chain

See Ownership Chain.

Brouter

A device that is the combination of a bridge and a router.

Brownout

A temporary decrease in the voltage level of power supplied to network devices. Brownouts are frequently called sags.

Browser

A computer on a Microsoft network that maintains a list of computers and services available on the network.

Browsing

The process of requesting the list of computers and services on a network from a browser.

Brute Force Attack

An attack in which each possible key or password is attempted until the correct one is found. See also Attack.

BSI

See Boot Sector Infector.

Buffer

A storage area dedicated to handling data while in transit. Buffers are used to receive/store sporadic deliveries of data bursts, usually received from faster devices, compensating for the variations in processing speed. Incoming information is stored until everything is received prior to sending data on. Also known as an information buffer.

Bug

An unintentional fault in a program that causes actions neither the user nor the program author intended.

Bulk Encryption Key

The random secret key generated by a client’s security DLL used to seal messages.

Bus (Linear Bus)

A network topology in which all computers are connected by a single length of cabling with a terminator at each end. The bus is the simplest and most widely used network design.

BUS

See Broadcast and Unknown Servers.

Business Model

A description of the business relationships within a company.

Bus Topology

A linear LAN architecture in which transmissions from various stations on the network are reproduced over the length of the medium and are accepted by all other stations.

BX.25

AT&T’s use of X.25. See also X.25.

Bypass Mode

An FDDI and Token Ring network operation that deletes an interface.

Bypass Relay

A device that enables a particular interface in the Token Ring to be closed down and effectively taken off the ring.

Byte

A set of 8 bits taken as a unit that represent up to 256 possible values. Because bytes are convenient for storing characters such as letters or numbers, they are the baseline used to measure memory sizes. See also Bit.

Byte-Oriented Protocol

Any type of data-link communication protocol that, in order to mark the boundaries of frames, uses a specific character from the user character set. These protocols have generally been superseded by bit-oriented protocols.