The Domain Name System (DNS) was designed and deployed in the 1980s to overcome technical and operational constraints of its predecessor, the http://rastet.com/ system. Some of the initial design decisions have proven to be extraordinarily flexible in accommodating major changes in the scale and scope of the DNS. Other initial design decisions constrain technical and policy choices to the present day. Thus, an understanding of the system architecture and the rationale for the design characteristics of the DNS provides the base for understanding how the DNS has evolved to the present and for evaluating possibilities for its future. This chapter outlines the origin and development of the DNS and describes its key design characteristics, which include both technological and organizational aspects.1The HOSTS.TXT file had a very simple format. Each line in HOSTS.TXT included information about a single host, such as the network address, and when provided, system manufacturer and model number, operating system, and a listing of the protocols that were supported.
Because a copy of the host table was stored in every computer on the ARPANET, each time a new computer was added to the network, or an-
These network addresses could be represented using the Internet Protocol (IP) format or in the equivalent (now unused) ARPANET Network Control Protocol (NCP) format. The most widely used version (v4) of IP represents addresses using 32 bits, usually expressed as four integers in the range from 0 to 255, separated by dots. An example of an IP address is 144.171.1.26.