37. Classless Inter-Domain Routing

• Around 1993 Classless Inter-Domain Routing (CIDR) scheme was introduced.

• CIDR allows re-division of class A, B and C networks.

• CIDR allocates blocks of IP addresses to specific local area networks:

  • Internet service providers (larger blocks)

  • ISP customers and small businesses (smaller blocks)

  • Businesses and companies with presence on the internet, etc.

• CIDR has hierarchical structure, overseen by the Internet Assigned Numbers Authority, IANA.

• More:

  • see Wikipedia articles Internet Protocol and IPv4