C

Cable Modem Termination System (CMTS) device

A device used to forward user data to the Internet. Downstream data from the Internet is forwarded to the cable television equipment in that neighborhood, where it is then forwarded to the home user.

caching

A process whereby information is retrieved from the network and is then stored locally for use later, when the network is not available.

central office

A building in a given neighborhood where all local phone lines in that neighborhood are terminated.

Central Processing Unit (CPU)

The microprocessor, or brain, of the computer. It uses logic to perform mathematical operations that are used in the manipulation of data.

child domain

A tree created under the namespace of an existing tree.

client

A computer on the network that requests network services.

client-server network

Uses a dedicated server to centralize user and group account management. Users at a client, or workstation, log on to a server where they have user accounts and access resources on the server to which their user account has permission.

clock signal

Controls the rate at which synchronous data is transmitted.

clustering

Connecting two or more computers to make them appear as one system. Clustering is used to take advantage of the processing power of multiple computers.

coaxial

A type of media that has a single copper wire surrounded by plastic insulation, is wrapped in metal braid or foil, and is protected by a plastic cover.

collisions

A problem on Ethernet networks that occurs when two computers transmit on the wire simultaneously, causing an electrical spike twice the strength than is normal for the network.

COMMAND.COM

A DOS operating system file that receives and executes commands as they are entered at the command line by the user.

command line

The prompt in a DOS screen from which a command is executed by typing letters and characters.

compact disc (CD)

A plastic or optical disk that can be read using lasers. All compact discs have a maximum storage capacity of 650MB.

compact disc-recordable (CD-R)

A compact disc that can have data recorded on it once using a laser and can be read many times.

compact disc-rewritable (CD-RW)

A compact disc that can have data rewritten to it several times using lasers. Lasers record data to the disc like a CD-R, but slightly less powerful lasers are used to erase the data. Even weaker lasers are used to read the data.

Complex Instruction Set Computing (CISC)

A full complement of instructions used by a processor to complete tasks such as mathematical calculations. Used in the most common type of processors produced; Intel processors are currently based on this standard.

compression

A method of reducing the size of data by using a mathematical calculation.

Computer Management utility

Used to monitor and configure the Windows 2000 Server and Windows Server 2003 computer. System tools, system drives, and services can all be configured from here.

CONFIG.SYS

A DOS or OS/2 file that contains special configuration settings in the form of line statements. The file is stored in the root of the C drive and is one of the key files read when an operating system boots.

connection oriented

A method of communication that is considered reliable because the sender is notified when data is not received or is unrecognizable.

console command

A command that is input directly from the keyboard and monitor of the server instead of remotely.

container

Any object in the directory into which other objects can be placed. Objects that do not have this capability are called leaf objects.

conventional memory

The first 640KB of memory, which is required by DOS to run. Memory above 640KB was used by operating systems such as Windows 3.1.

cyclic redundancy check (CRC)

A form of error detection that performs a mathematical calculation on data at both the sender's end and the receiver's end to ensure that the data is received reliably.