Glossary

Chief information security officer

Cipher

A cryptographic algorithm for encryption and decryption.

Ciphertext

Ciphertext is the encrypted form of the message being sent.

Circuit Switched Network

A circuit switched network is where a single continuous physical circuit connected two endpoints where the route was immutable once set up.

Classful network

A classful network is a network addressing architecture used in the Internet from 1981 until the introduction of Classless Inter-Domain Routing in 1993. The method divides the address space for Internet Protocol Version 4 (IPv4) into five address classes by address range. Classes A, B, C are networks of three different network sizes, i.e. number of hosts for unicast addresses. Class D is for multicast. The class E address range is reserved for future or experimental purposes. Under classful networking, the subnet mask was implied by which address range (class) the address occupied and did not need to be specified separately.

Classless Interdomain Routing (CIDR)

Classless Inter-Domain Routing is a method for allocating IP addresses and IP routing.

Client

A system entity that requests and uses a service provided by another system entity, called a "server." In some cases, the server may itself be a client of some other server.

Cold/warm/hot Disaster Recovery Site

* Hot site. It contains fully redundant hardware and software, with telecommunications, telephone and utility connectivity to continue all primary site operations. Failover occurs within minutes or hours, following a disaster. Daily data synchronization usually occurs between the primary and hot site, resulting in minimum or no data loss. Offsite data backup tapes might be obtained and delivered to the hot site to help restore operations. Backup tapes should be regularly tested to detect data corruption, malicious code and environmental damage. A hot site is the most expensive option.* Warm site.It contains partially redundant hardware and software, with telecommunications, telephone and utility connectivity to continue some, but not all primary site operations. Failover occurs within hours or days, following a disaster. Daily or weekly data synchronization usually occurs between the primary and warm site, resulting in minimum data loss. Offsite data backup tapes must be obtained and delivered to the warm site to restore operations. A warm site is the second most expensive option.* Cold site.Hardware is ordered, shipped and installed, and software is loaded. Basic telecommunications, telephone and utility connectivity might need turning on to continue some, but not all primary site operations. Relocation occurs within weeks or longer, depending on hardware arrival time, following a disaster. No data synchronization occurs between the primary and cold site, and could result in significant data loss. Offsite data backup tapes must be obtained and delivered to the cold site to restore operations. A cold site is the least expensive option.