Domain Names Part I Continued

History of the Domain Name System

The purpose of the domain name system is to allow any computer on the Internet to figure out what IP address (for example, 216.112.23.10) corresponds with a particular computer hostname (for example, "www.ahref.com"), and also what hostname, if any, corresponds with an IP address. Your computer needs to know remote computers' IP addresses to figure out how and where to send things like email messages and requests for web pages.

How It Used to Work

The domain name system started out as just a single file, "hosts.txt." The late Dr. Jon Postel, then at UCLA, was the first person to maintain this file, under a contract with the Department of Defense; the list was published by SRI International, via an FTP server. The file contained information on all the host computers connected to the ARPANET, and later its successor, the Internet. This information included the hostname and IP address of each host. As the number of hosts on the Internet increased, and Dr. Postel moved on to other duties, SRI took on the responsibility of maintaining the file, in addition to making it publicly available.

Administrators who wanted to change information about their hosts would email the changes to SRI. SRI would change the hosts.txt file every few days, and administrators would periodically FTP that file from SRI's server. This system worked for many years, but did not scale well - the load on SRI's server from the constant FTP requests, and the administrative load of dealing with changes, became too high to deal with, once the number of hosts increased to more than just a few hundred.

In 1984, the System Changed

In 1984, Paul Mockapetris (then at USC's Information Sciences Institute) designed the architecture of the new Domain Name System, describing, in RFCs 882 and 883, the system which we still use today for mapping hosts and domains to IP addresses and actual machines. (These RFCs - Requests For Comments - were later superseded by RFCs 1034 and 1035).Under this system, DNS information is spread across the Internet; there is no one machine that maintains information on all hostnames. Each domain owner maintains information on their own hosts. A central authority keeps records on where each domain owner keeps their information.

The maintenance of the Internet and the Domain Name System continued under contract to the Department of Defense, and DOD agencies, for many years. Then, in 1991, the National Science Foundation (NSF) assumed responsibility for the non-military portion of the Internet. In 1992, the NSF awarded NSI a contract for managing the registration of domain names and maintenance of domain name information. Since then, NSI has had a government-sponsored monopoly on the registration of second-level domains (for example, ahref.com and linux.org) under the generic top-level domains (gTLDs): .com, .org, .net, and .edu. The Internet Assigned Names Authority (IANA), among other responsibilities, continued to manage the allocation of IP addresses, and continues to do so, pending the transfer of these responsibilities to ICANN.

(A note on other top-level domains: The military and government, respectively, administer the .mil and .gov hierarchies. There are also more than 200 national or country-code top-level domains (ccTLDs), each maintained by their corresponding governments or authorized agents of those governments. IANA maintains a list of the ccTLDs, and contact informaton for their administrators, on their website. The .us ccTLD is administered by The US Domain Registry at the Information Sciences Institute of the University of Southern California, and is currently being eyed by the US Postal Service.)

NSI's Contract Runs Out

NSI's contract to administer the main top-level domains expired on September 30, 1998. On September 29, the government awarded a 7-day extension to the contract. On October 8, the U.S. government granted a longer and more detailed extension, under which NSI's responsibilities for domain name registration could theoretically continue through September 30, 2000, but which also includes provisions for NSI's responsibilities to be gradually transferred to a new organization (referred to as "NewCo" in the amendment document).

That new organization, charged with taking over and revamping the domain name system, as well as other Internet infrastructure responsibilities, is the Internet Corporation for Assigned Names and Numbers (ICANN).

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