Before the Domain Name System, the entire ARPANET shared one file. HOSTS.TXT was a plain text table listing every host’s official name, its network address, and basic attributes. The idea was set out as early as January 1974 in RFC 608, “Host Names On-Line,” which proposed that the Network Information Center maintain “an online ASCII text file of Host names, addresses, and attributes.” Every machine on the network kept a copy of this file and consulted it locally to translate a name into an address.
RFC 952, “DoD Internet Host Table Specification” (October 1985), defined the file’s exact format and where to get it. The authoritative copy lived at SRI’s Network Information Center: “A machine-translatable ASCII text version of the DoD Host Table is online in the file NETINFO:HOSTS.TXT on the SRI-NIC host.” Administrators retrieved it by anonymous FTP from SRI-NIC.ARPA, logging in “as user = ANONYMOUS, password = GUEST,” and pulling down the latest version.
This centralized scheme worked while the network was small, but it carried structural problems that grew with it. There was a single point of authority and a single point of failure: every name change had to be sent to the NIC, merged into the master file, and then redistributed to every host on the network. As the number of hosts climbed, the file grew larger, edits grew more frequent, and the bandwidth and effort of pushing fresh copies everywhere became unsustainable. Name collisions also became harder to avoid when one office had to be the gatekeeper for the whole namespace.
These were exactly the pain points that DNS was designed to remove. Paul Mockapetris’s distributed, hierarchical naming system replaced the one flat file with a delegated tree, so that organizations could manage their own names without routing every change through a central registrar. HOSTS.TXT did not disappear overnight, and the same idea survives in miniature: most operating systems still ship a local hosts file that takes precedence over DNS lookups, a small descendant of the table that once held the whole internet.