Network Terms "C"

Network Glossary and acronym's

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

.CDF file

Channel Definition Format files. Text files that contain a personalized index for a Web site, so you can download only the content that interests you. Using a .CDF converts a Web site into a channel.

.CHK file

Exchange 2007's database engine is referred to as the Extensible Storage Engine (ESE). ESE is a transactional database that writes information into RAM memory and into a log file. Once it is in the log file, it will be written to disk. There are a number of files used to store information:

An .edb file is located in the actual database itself. All of a user's messages, folders, public folders, contacts, appointment information, etc. is all stored on the .edb file. An .edb file size can exceed multiple GB.
A .log file is an ESE transaction log file. All .log files are 1 MB.
A .jrs file is a reserve log file which is used to commit any transactions that are still in memory in the event of the server running out of disk space. All .jrs files are 1 MB.
A .chk file is used to identify which log files have been committed to the database. The size of .chk file varies from 2-3 KB.

The ESE takes the following steps to write information into database files:

The ESE writes a message into memory RAM when it arrives at the server.
At the same time that information is written to RAM, it's written into the current .log file. All current log files are named E00.log. The information is written in a sequential format until the log file is full. When the log file is full, it will be renamed.
Once it has been committed to the log file, the information is written to the .edb file.
The checkpoint file is updated to indicate that the transaction log that has been committed to the database.

.CSV file

A comma-delimited text file.

Cache

A file that contains host information needed to resolve names outside of authoritative domains. It also contains names and addresses of root name servers.

Cache Manager

A part of the I/O Manager that improves a computer's performance by temporarily storing files in memory instead of reading and writing them to the hard disk. The Cache Manager uses virtual address space to cache data.

CAL (Client Access License)

A client access license permits a client to connect to a Windows 2000 server.

Callback

A remote access server configuration that provides network security by restricting network access to a specified list of phone numbers. When a client calls the server, the server hangs up, then calls the client back at the appropriate phone number.

Canonical Name (CNAME) record

Enables you to associate more than one host name with an IP address. This concept is also referred to as aliasing.

Carrier Sense Media Access/Collision Avoidance (CSMA/CA)

CSMA/CA is the technology used by Ethernet and wireless networks to control media access and avoid (rather than detect) collisions. CSMA/CD works as follows:

If a host detects traffic on the network, it experiences a longer back-off time than hosts on a wired network before attempting to transmit again.
Every transmission must be acknowledged. As every frame is acknowledged by the receiving host, other hosts receive a message indicating that they must wait to transmit.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

CSMA/CD is the technology used by Ethernet. CSMA/CD works as follows:

The system listens for traffic, if the line is clear it begins transmitting.
During the transmission, the system listens for collisions.
If no collisions are detected, the communication succeeds. If collisions are detected, an interrupt jam signal is broadcast to stop all transmissions. Each system waits a random amount of time before starting over at step 1.

CAS (Client Access server)

Client Access server role is required in every Exchange 2007 organization because it supports the client applications Outlook Web Access and Exchange ActiveSync and also the Post Office Protocol version 3 (POP3), and Internet Message Access Protocol version 4rev1 (IMAP4) protocols.

Cascading physical star

A logical ring topology created with the FDDI standard. In this topology, single-attachment hubs connect single-attachment stations to a network.

Case sensitive

All capital and lower-case characters must be typed exactly as they appear. For example, if the password was "Himalayas" and you typed "himalayas," you would not be allowed to log on.

CCR (Local Continuous Replication)

Cluster Continuous Replication (CCR) combines the asynchronous log shipping and replay technology of Exchange 2007 with the failover and management features provided by the Microsoft Windows Cluster service. CCR does not have a single point of failure and provides high availability by replicating data on a passive node, so the clustered Mailbox server can operate on either node at any time.

CD File System (CDFS)

A read-only file system for CD-ROMs, supported by Windows 2000.

CDFS (CD File System)

A read-only file system for CD-ROMs, supported by Windows 2000.

Central Processing Unit (CPU)

The logic circuitry that responds to instructions and runs the computer. Also called a processor.

Centralized computing

A configuration in which all the data and applications are stored and executed on a mainframe computer. The terminals act only to accept keystrokes on the keyboard and display data from the mainframe computer.

Centralized network administration

The ability to manage network resources from a centralized database location. The Windows 2000 directory service provides the capability to manage resources centrally.

Certificate

A digitally signed statement issued by a Certification Authority (CA). It contains a public key and certifies that a specific person, organization, device, or service is the only holder of the corresponding private key. Certificates commonly use the ITU-T X.509 international standard.

Certificate authority

A certificate authority (CA) is the component of the public key infrastructure entrusted to issue, store, and revoke certificates. A certificate authority accepts certificate requests, verifies the information provided by the requester, creates and digitally signs the certificate, and issues the certificate to the requester. It also revokes certificates and publishes a certificate revocation list (CRL).

Certificate Revocation List (CRL)

Digital certificates usually expire after one year, but CAs can revoke certificates earlier for various reasons. All revoked certificates are stored in the certification revocation list, which is open to all users. This allows users to check the list to verify whether a given certificate is valid.

Certificate Services

The Microsoft Windows 2000 component that lets a system administrator create a certificate authority to issue, revoke, and manage digital certificates as part of a public key infrastructure.

Certification Authority server

A Certification Authority server creates new encryption keys for clients and publishes public keys for users. The Exchange KM Server is a Certification Authority server.

CGI (Common Gateway Interface)

A software program that allows Web servers to send data to an application and receive information back from the application, regardless of the operating system the application is running under.

CGMP(Cisco Group Management Protocol)

Cisco Group Management Protocol (CGMP) is a Cisco proprietary protocol that works between the router and the switch. In CGMP, the switch only allows multicast traffic to flow through specific ports according to client data from the router instead of flooding data across all ports. CGMP:

Enables routers to inform each of their directly-connected switches of IGMP registrations from hosts accessible through the switch.
Forwards multicast traffic only to ports on which the requesting routers are located.
Is the most common multicast switching solution.
Is based on a client/server model in which the router acts as a server and the switch acts as a client.

Challenge Handshake Authentication Protocol (CHAP)

CHAP is an authentication encryption protocol designed to protect passwords while in transit from a client to the logon server.

CHAP periodically verifies the identity of a peer using a three-way handshake. CHAP ensures that the same client or system exists throughout a communication session by repeatedly and randomly re-testing the validated system. This test involves the security server sending a challenge message to the client. The client then performs a one-way hash function on the challenge and returns the result to the security server. The security server performs its own function on the challenge and compares its result with that received from the client. If they don't match the session is terminated.

Channel Service Unit/Data Service Unit (CSU/DSU)

A hardware device that converts a digital data frame from a LAN format into a WAN format and vice versa.

Channels

Web sites that you can customize with a .CDF file to give you only the information that you want to see. When you subscribe to a channel, Internet Explorer monitors the Web sites included in the channel and downloads only the information that fits the channel's parameters.

CHAP (Challenge Handshake Authentication Protocol)

CHAP is an authentication encryption protocol designed to protect passwords while in transit from a client to the logon server.

Character set

A set of 256 letters, digits, and symbols specific to a country or language. The character set selected during SQL installation specifies the characters SQL Server will recognize in the various data types. The first 128 values are called printable characters, and the last 128 values are called extended characters. Printable characters are the same for each set; extended characters vary from set to set. See also Unicode characters.

Checkpoint

A marked point in a SQL transaction log. It represents a point at which completed transactions and modified database pages were written to disk.

Chkdsk

An MS-DOS utility you can use to scan and repair both FAT and Windows NT NTFS volumes.

CIDR (Classless Inter-Domain Routing)

A technique used to collapse Class C entries into a single entry corresponding to all the Class IDs that are being used by that organization. This allows companies to use many Class C addresses rather than requesting a Class B address, since the availability of IP addresses is scarce.

Circuit Switching

A circuit switched network uses a dedicated connection between sites. Circuit switching is ideal for transmitting data that must arrive quickly in the order it is sent, as is the case with real-time audio and video.

Circuit-level Gateway

A circuit-level gateway monitors traffic between trusted hosts and un-trusted hosts via virtual circuits or sessions. A circuit-level gateway:

Verifies sequencing of session packets.
Hides the private network from the public network.
Does not filter packets. Rather it allows or denies sessions.

Circular logging

Circular logging is a logging method in which older logs are overwritten with new logging information. This method saves disk space but does not provide as much fault tolerance.

Cisco Group Management Protocol (CGMP)

Enables routers to inform each of their directly-connected switches of IGMP registrations from hosts accessible through the switch.
Forwards multicast traffic only to ports on which the requesting routers are located.
Is the most common multicast switching solution.
Is based on a client/server model in which the router acts as a server and the switch acts as a client.

Class A address

An IP address range that is assigned to networks with very large numbers of hosts. The Class A address assigns the high order bit to zero. The next seven bits complete the network ID portion of the address. The remaining 24 bits make up the host ID. The address range for the first octet (8 bits) is 1-126.

Class B address

An IP address range that is assigned to networks with medium to large networks. The Class B address assigns the two high order bits to binary 1 0 . The next 14 bits complete the network ID. The last 16 bits are used for the host ID. The address range for the first octet (8 bits) is 128 B 191.

Class C address

An IP address range that is used for small local area networks. The Class C address assigns the three high order bits to binary 1 1 0. The next 21 bits are used to complete the network ID. The last 8 bits are used to represent the network ID. The address range for the first octet (8 bits) is 192 B223.

Classful IP addresses

Classful addresses are IP addresses that use the default subnet mask.

Classful routing protocols

Classful routing protocols do not include default subnet mask information in routing updates. The default subnet mask is used to identify the network and host portions of the address. Classful routing protocols are:

Interior Gateway Routing Protocol (IGRP)
Routing Information Protocol version 1(RIPv1)

Classless Inter-Domain Routing (CIDR)

Classless IP addresses

Classless addresses are IP addresses that use a custom mask value to separate network and host portions of the IP address.

Classless routing protocols

Classless routing protocols use a custom mask value to separate network and host portions of the IP address. They are considered to be second-generation protocols because they improve on the limitations of classful protocols. The most common routing protocols are:

Enhanced Interior gateway Routing Protocol (EIGRP)
Intermediate System-to-Intermediate System (IS-IS)
Open Shortest Path First (OSPF)
Routing Information Protocol version 2 (RIPv2)

Client

A computer that uses files and resources from another computer on a network. Also called a workstation.

Client Access License (CAL)

A client access license permits a client to connect to a Windows 2000 server.

Client Access server (CAS)

Client Service for NetWare (CSNW)

A service included with Windows 2000 that allows a Windows workstation to use file and print resources residing on NetWare servers.

Client-based administration tools

Tools that allow you to perform several network administration tasks from a Windows 95/98 or Windows 2000 Professional workstation, such as creating users and groups, sharing folders, and assigning permissions to access resources.

ClipBook Viewer

A Windows shared resource that uses OLE to store up to 127 pieces of information, each called a ClipBook Viewer Page. Users can create and share these pages for use in OLE applications.

CLNS (Connectionless Network Service)

Connectionless Network Service (CLNS) is an address family that is used to identify routing sessions for protocols that use standard network service access point (NSAP) address prefixes, such as BGP.

Cluster Continuous Replication (CCR)

Clustering

A situation in which groups of independent computers work together as a single system.

CNAME (Canonical Name) record)

Enables you to associate more than one host name with an IP address. This concept is also referred to as aliasing.

Coaxial Cable

Coaxial cable is a type of network transmission media. It is an older technology that is usually implemented with a bus topology. It is not suitable for ring or star topologies because the ends of the cable must be terminated. It is composed of two conductors, which share a common axis, within a single cable.

Cold Site

A cold site is a fault tolerant strategy which provides a redundant work location. If a disaster renders a work site unusable, the effected organization may have a cold site in which to relocate. Cold sites have the following characteristics:

This is the least ready of alternative site types, but it is probably the most common.
The site is ready for equipment to be brought in during an emergency because there is no hardware on site.
The site might have electrical power and HVAC, but it may or may not have communication links.
A cold site is low cost, and may be better than nothing.
A cold site often offers a false sense of security. The actual amount of work involved in getting a cold site up and running might be more than expected and might take too long to adequately keep the business running.

Cold Spare

A cold spare is a component that sits on the shelf until there is a failure. Cold spares obviously need more time to implement recovery, but they don't have the maintenance requirements of hot spares.

COM (Component Object Model)

A method that allows objects to communicate with each other. It is the basis for both OLE and ActiveX.

Command line switches

Codes you can use at the command prompt when starting an application or installation program to customize the way the program runs.

Command prompt

The 32-bit Windows command-line interface similar to the MS-DOS prompt. You can use it to start programs and type Windows commands.

Common Gateway Interface (CGI)

A software program that allows Web servers to send data to an application and receive information back from the application, regardless of the operating system the application is running under.

Community

A community is a group that contains hosts that are running the SNMP service. These communities are identified by a community name and provide the first level of security and context checking for agents.

Community attribute

The community (type code 8) is an optional BGP transitive attribute that filters incoming or outgoing routes. BGP communities are routes that share some common properties and policies, which allows routers to act on the community as a whole rather than on individual routes.

Complete trust domain model

In this Windows NT network model, every domain on the network trusts every other domain. No single domain has control over the other domains. The complete trust model distributes administration of users, groups, domains, and resources among different departments rather than using a centralized approach.

Component Object Model (COM)

A method that allows objects to communicate with each other. It is the basis for both OLE and ActiveX.

Computer account

An account entry in the local SAM database or the Active Directory domain database that identifies a computer (workstation) as part of a domain.

Configuration container

The configuration container is used to store information about the configuration of the Active Directory environment in Exchange 2007, such as site configuration and areas of optimal connectivity. When AD is employed over a WAN, a site for each end of the WAN link is defined along with the site link that represents the WAN connection. Exchange 2007 uses this site information to route messages within the environment. The configuration container also contains additional Exchange configuration such as the definition of the connectors within the environment, the accepted domains, and which servers hold which roles.

Configuration partition

An Active Directory partition that stores the domain, site, and replication structure of a Windows 2000 network.

Connection object

An Active Directory object that represents a uni-directional connection between a source and target replication partner over which Active Directory data is replicated.

Connectionless communication

Connectionless communications assume an existing link between devices and allow transmission without extensive session establishment. Connectionless communications use no error checking, session establishment, or acknowledgements. Connectionless protocols allow quick, efficient communication at the risk of data errors and packet loss. Connectionless protocols are a good choice where speed is important and smaller chunks of data are being sent.

Connectionless Network Service (CLNS)

Connectionless Network Service (CLNS) is an address family that is used to identify routing sessions for protocols that use standard network service access point (NSAP) address prefixes, such as BGP.

Connection-oriented communication

Connection-oriented communication does not assume that there is an existing link between devices. Connection-oriented communications use error detection/correction, session establishment, or acknowledgements, and, if necessary, retransmission. Connection-oriented communication provides a more reliable communication when are delivery is more important than speed and is a good method to use when larger chunks of data are being sent.

Console

The Microsoft Management Console (MMC) is a graphical interface for the administration of Windows 2000 and some earlier Microsoft operating systems. It accommodates various "snap-in" tools.

Console tree

The left pane of the Microsoft Management Console (MMC). It shows a hierarchical structure of functions and/or objects.

Control Panel

A Windows utility that displays other utilities that are used to manage the local computer.

Convergence

A routing metric is a value used by routing protocols to determine the length of paths within a network. Different routing protocols use various measurements to calculate metrics, such as:

Bandwidth
Network delay
Hop count
Interface speed
Path cost
Load
MTU
Reliability
Communication cost

Marker downloaded from Internet servers and stored on the hard drives of client computers. Cookies store information about your preferences, browser settings, location, and so on. They identify you (or your browser) to Web sites.

Cooperative multitasking

A system in which each application currently running a process voluntarily passes control of the CPU to another application between processes. It is also called non-preemptive multitasking.

Copy backup

A specific type of backup that backs up selected files and folders but does not mark their archive attributes.

CPU (Central Processing Unit)

The logic circuitry that responds to instructions and runs the computer. Also called a processor.

CRC (Cyclic Redundancy Checking)

Cyclic redundancy checking is a method used to verify correct transmission and reception of data that has been sent across a network.

Creator Owner

A built-in group that is used for network administration. It includes the user that created or took ownership of a resource.

CRL (Certificate Revocation List)

Crossover cable

A cable connecting one hub with another hub or with a repeater in a network.

CSMA/CA (Carrier Sense Media Access/Collision Avoidance)

CSMA/CA is the technology used by Ethernet and wireless networks to control media access and avoid (rather than detect) collisions. CSMA/CD works as follows:

If a host detects traffic on the network, it experiences a longer back-off time than hosts on a wired network before attempting to transmit again.
Every transmission must be acknowledged. As every frame is acknowledged by the receiving host, other hosts receive a message indicating that they must wait to transmit.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)

CSMA/CD is the technology used by Ethernet. CSMA/CD works as follows:

The system listens for traffic, if the line is clear it begins transmitting.
During the transmission, the system listens for collisions.
If no collisions are detected, the communication succeeds. If collisions are detected, an interrupt jam signal is broadcast to stop all transmissions. Each system waits a random amount of time before starting over at step 1.

CSNW (Client Service for NetWare)

A service included with Windows 2000 that allows a Windows workstation to use file and print resources residing on NetWare servers.

CSR subsystem

The Windows subsystem that supports 32- and 16-bit Windows and MS-DOS applications within Windows 2000. Also called the Win32 subsystem, client/server subsystem, or CSRSS.

CSU/DSU (Channel Service Unit/Data Service Unit)

A hardware device that converts a digital data frame from a LAN format into a WAN format and vice versa.

Custom subnet mask

A subnet mask that is defined by a network administrator. Each host on a TCP/IP network requires a subnet mask. If a custom subnet mask is not used, then a default subnet mask is automatically used.

Cyclic Redundancy Checking (CRC)

Cyclic redundancy checking is a method used to verify correct transmission and reception of data that has been sent across a network.