DNS on Windows Server 2003, 3rd Edition

The History of the Domain Name System

Through the 1970s, the ARPAnet was a small, friendly community of a few hundred hosts. A single file, HOSTS.TXT , contained a name-to-address mapping for every host connected to the ARPAnet. The familiar Unix host table, /etc/hosts, was compiled from HOSTS.TXT (mostly by deleting fields Unix didn’t use).

HOSTS.TXT was maintained by SRI’s Network Information Center (dubbed “the NIC”) and distributed from a single host, SRI-NIC.^[1] ARPAnet administrators typically emailed their changes to the NIC and periodically ftped 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. The size of HOSTS.TXT grew in proportion to the growth in the number of ARPAnet hosts. Moreover, the traffic generated by the update process increased even faster: every additional host meant not only another line in HOSTS.TXT, but potentially another host updating from SRI-NIC.

When the ARPAnet moved to TCP/IP, the population of the network exploded. Now there was a host of problems with HOSTS.TXT (no pun intended):

Traffic and load

The toll on SRI-NIC, in terms of the network traffic and processor load involved in distributing the file, was becoming unbearable.

Name collisions

No two hosts in HOSTS.TXT could have the same name. However, while the NIC could assign addresses in a way that guaranteed uniqueness, it had no authority over hostnames. ...