HOSTS.TXT

HOSTS.TXT was maintained by SRI’s Network Information Center (dubbed “the NIC”) and distributed from a single host, SRI-NIC.[*] ARPAnet administrators typically emailed their changes to the NIC, and periodically FTP’ed to SRI-NIC and grabbed the current HOSTS.TXT file. Their changes were compiled into a new HOSTS.TXT file once or twice a week. As the ARPAnet grew, however, this scheme became unworkable. (Liu and Albitz 2006, 3)

The size of HOSTS.TXT grew in proportion to the growth in the number of ARPAnet hosts, which brought issues like:

Traffic and load
Collisions
Searching the file was linear (O(n)).

The ARPAnet's governing bodies chartered an investigation to develop a successor for HOSTS.TXT, solving all issues of its centralized design.

Paul Mockapetris, then of USC's Information Sciences Institute, was responsible for designing the architecture of the new system. In 1984, he released RFCs 882 and 883, which described the Domain Name System. (Liu and Albitz 2006, 4)

References:

Liu, Cricket, and Paul Albitz. 2006. Dns and Bind. O’Reilly Media, Inc.