IP Address

Evolution of the IP address

May 1974, A Protocol for Packet Network Intercommunication, 8-bit network ID, 16-bit host ID
December 1974, RFC 675, 4-bit network ID length, 4-bit network ID, 16 bit "TCP address"
March 1977, IEN 5, 8-bit network ID, 24-bit host ID (IPv0)
January 1978, IEN 21, 8-bit network ID, variable length host ID (IPv1)
February 1978, IEN 26, 8-bit network ID, 24-bit host ID
February 1978, IEN 28, 4-bit address length, variable length address
June 1978, IEN 41, 8-bit address length, variable length address
January 1980, RFC 760, 8-bit network address, 24-bit local address (IPv4)
September 1981, RFC 791, 32-bit address, with three defined classes (A–C) (IPv4)