`HOSTS.TXT` system in use

Beginning around 1971, SRI International's Network Information Center (NIC) began maintaining a single text file, `HOSTS.TXT`, which mapped hostnames to IP addresses for the ARPANET. This file was distributed to all connected hosts.

Significance

This centralized file was the Internet's original naming system, proving the concept of symbolic names but also highlighting the scalability problems that DNS would later solve.