Timeline milestone
IANA Allocates the Last Free IPv4 Address Blocks
From How the Internet Was Built: From Four Computers to a Global Network
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Infrastructure
IANA Allocates the Last Free IPv4 Address Blocks
On 3 February 2011, IANA allocated its remaining five /8 blocks of IPv4 addresses, one to each Regional Internet Registry, emptying the global free pool of new IPv4 space for the first time in the protocol's history. The moment gave registries and providers a clear signal that future growth would depend on IPv6, adding urgency to the coordinated push that culminated the following year in World IPv6 Launch.
IPv4, the addressing scheme underlying the Internet since the 1980s, provides roughly 4.3 billion unique addresses, a number that seemed enormous when the protocol was designed but became visibly insufficient as billions of new devices, phones and always-on connections joined the network. On 3 February 2011, IANA allocated its last five available address blocks, one to each Regional Internet Registry, emptying the central free pool for the first time in the protocol's history; individual registries continued issuing from their own remaining stock for some years after. The depletion turned IPv6 adoption from a long-discussed future option into an operational necessity, since no further IPv4 space could be created to meet growing demand, setting up the coordinated push that culminated the following year in World IPv6 Launch.
