How did ARPANET computers find each other before DNS, according to Paul Mockapetris?

Paul Mockapetris says every host was listed in a single text file maintained by the SRI NIC, mapping machine names to addresses. Adding a computer meant phoning SRI, ideally during Pacific business hours, and a new machine only became known as other sites downloaded fresh copies of that file. It was about 50 lines when he started with computers and a couple of hundred lines when he began designing DNS around 1982.

• The SRI NIC grew from three people to about 20 staff handling name requests, paid for by the Department of Defense.
• With DNS, an organisation registered once and then managed its own computers, with changes visible immediately.

Source: our own transcription of the episode. The full conversation is on Ryan Peterman (2026-10-19). Read the whole episode summary →

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