ICANN hands out last IPv4 addresses, sets clock ticking for IPv6
In February, the Internet Assigned Numbers Authority (IANA), operated by the Internet Corporation for Assigned Names and Numbers, handed out its last IPv4 addresses, allocating the final five blocks of 16 million addresses to each of five regional Internet registries (RIRs). The imminent depletion of IPv4, which provided 4.3 billion addresses, is a sign of how quickly the Internet has grown, and puts pressure on ISPs and companies to switch to its successor, IPv6. Though some regions might not exhaust their supply of IPv4 addresses for several years, Internet communications could break down over time unless network managers migrate to IPv6, which allows for better security, better network management and what's thought to be an inexhaustible supply of addresses. IPv6-based hosts will not be able to communicate with IPv4-only systems without techniques that could impair Internet communications.