How the Internet got its addresses (and why they weren't enough)

I’m always fascinated/impressed/surprised (maybe all of the above!) by how the Internet came to be, and how it was never planned to be this successful. I’m working on something related to IP address space, so let me share one of my favourite examples.

In 1977, Vint Cerf had to decide how many addresses the Internet would need. He was running the Defense Department’s Internet research program. The engineers had argued about address size for a year without agreeing, so Cerf picked one himself: 32-bit numbers, about 4.3 billion addresses. That seemed plenty for what was still an experiment.

When that format was published as RFC 791 in September 1981, the ARPANET had 213 host computers. “The problem is the experiment never ended,” Cerf said in 2010.

The addresses were handed out as if they would never run short, and some of the biggest blocks went to some interesting organisations — Ford among them. More on that later.

Cerf has told the story many times, and always takes the blame. At the University of Maryland in 2009, describing the moment he ended the debate, he said: “Let’s go do something. Here we are. My fault.”

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