What is CIDR (Classes Inter-Domain Routing)?

Classless Inter-Domain Routing (CIDR) is also known as supernetting. It is an approach to more flexibly assign Internet Protocol (IP) addresses by making granular identifiers for networks and individual devices. It was presented in 1993 as an alternative to Internet routers that controlled network traffic dependent on the class of IP addresses and decided subnetworks for routing, based on IP address class. Its objective was to moderate the development of routing tables on routers across the Internet and to help slow the rapid exhaustion of IPv4 addresses.