A network segment that acts as a trunk between other network segments. Backbones are typically high-bandwidth implementations such as fiber-optic cable.
backup schedule
A document or plan that defines what type of backups are made, when, and what data is backed up.
bandwidth
The width of the range of electrical frequencies, or amount of channels that the media can support. Bandwidth correlates to the amount of data that can traverse the media at one time, but other factors determine what the maximum speed supported by a cable will be.
baseband
A term applied to any media capable of carrying only a single data signal at a time. Compare with broadband.
baseline
A measurement of performance of a device or system for the purposes of future comparison. Baselining is a common server administration task.
baud rate
The speed or rate of signal transfer. Baud rate bandwidth is measured in cycles per second, or hertz (Hz). The word baud is derived from the name of French telegraphy expert J. M. Baudot.
binary
A base 2 numbering system that is used in digital signaling. It uses only the numbers 1 and 0.
Bindery
The name of the user account information database on NetWare servers up to and including NetWare 3.x.
binding
The process of associating a protocol with a NIC.
biometrics
The science and technology of measuring and analyzing biological data. Biometrics is used for security purposes to analyze and compare characteristics such as voice patterns, retina patterns, and hand measurements.
BIOS(Basic Input/Output System)
A basic set of instructions that a device needs to operate.
bit
An electronic digit used in the binary numbering system. Bit is a contraction of the terms binary and digit.
blackout
A total loss of electrical power.
Blue Screen of Death
The term for the blue-screen STOP errors that occur on and halt a Windows systems.
Bluetooth
A low-cost, short-range RF technology designed to replace many of the cords that are used to connect devices. Bluetooth uses 2.4Ghz RF and provides transmission speeds up to 16Mbps.
BNC(Bayonet Neill Concelman)
A family of connectors typically associated with thin coaxial cabling and 10Base2 networks. BNC connectors use a twist and lock mechanism to connect devices to the network.
bound media
A term used to describe any media that have physical constraints, such as coaxial, fiber-optic, and twisted pair. Compare with unbound media.
boundless media
See [unbound media]
BRI(Basic Rate Interface)
An ISDN digital communications line that consists of three independent channels: two B channels, each at 64Kbps, and one D channel, at 16Kbps. ISDN BRI is often referred to as 2B+D.
See also [ISDN]
See also [PRI]
bridge
A device that connects and passes traffic between two network segments that use the same communications protocol. Bridges operate at the data-link layer of the OSI model. A bridge filters, forwards, or floods an incoming frame based on the MAC address of that frame.
bridging address table
A list of MAC addresses that a bridge keeps and uses when it receives packets. The bridge uses the bridging address table to determine which segment the destination address is on before it sends the packet to the next interface or drops the packet (if it is on the same segment as the sending node).
broadband
A communications strategy that uses analog or digital signaling over multiple communications channels.
broadcast
A packet delivery system in which a copy of a packet is given to all hosts attached to the network.
broadcast storm
An undesirable condition in which broadcasts become so numerous as to bog down the flow of data across the network.
brouter
A device that can be used to combine the benefits of both routers and bridges. Its common usage is to route routable protocols at the network layer of the OSI model and to bridge nonroutable protocols at the data-link layer.
brownout
A short-term decrease in the voltage level, usually caused by the startup demands of other electrical devices.
buffer
An area of memory in a device that is used to store data before it is forwarded to another device or location.
bus topology
A linear LAN architecture in which all devices are connected to a common cable, referred to as a bus or backbone.
byte
A set of bits (usually 8 bits) that operates as a unit to signify a character.
