IPv4 was developed back in the Dark Ages of the Internet – 1978. The 32-bit address space allowed for 4 billion addresses, which seemed like a good idea at the time. In 1993, IETF forecasts showed IPv4 addresses running out sometime between 2010 and 2017, so engineers began work on IPv6, which was completed in 1999.
Stories by Lee Schlesinger
In February 2011, the global Internet Assigned Numbers Authority (IANA) allocated the last blocks of IPv4 address space to the five regional Internet registries. At the time, experts warned that within months all available IPv4 addresses in the world would be distributed to ISPs.