If it hadn't been for all the uproar about how top-level domain names were assigned, the international community might never have taken much interest in the root server system. Top-level domains — the letters (usually two or three) that come after the final dot in an Internet address — are assigned for all countries by the Internet Corporation for Assigned Names and Numbers, or ICANN, a U.S.-based non-profit organization.

When people in other countries began to complain a few years ago that they were having trouble getting top-level domains, it brought to light concerns about how ICANN was structured, how it operated and the fact that it was overseen by the U.S. Department of Commerce. Concerns also were raised about the arcane root server system, which is perhaps the last vestige of the academic and research network that was the original Internet.

The root server system has a single purpose — to tell Internet users where to go to find the owner of an Internet address. (For “.com” addresses, for example, it points people to a server system operated by VeriSign, which administers “.com” domain names.) According to a popular myth, there are only 13 root servers to handle all the world's Internet traffic. That's not quite true. But what is true is that the root server system is operated by 12 (primarily U.S.-based) organizations, which together operate a few hundred servers on which the world's Internet traffic depends.

Those 12 organizations include entities as diverse as the University of Maryland, the U.S. Army Research Lab and Cogent Communications, which inherited the responsibility when it acquired the assets of defunct ISP PSINet. (A quirk in protocol structure makes it impractical to have more than 13 root server administrators. VeriSign, in addition to its “.com” responsibilities, operates two root server systems, narrowing the field to 12.) They got their responsibility in the earliest days of the Internet, and there is no process for reviewing or renewing them. Like Supreme Court justices, they essentially have been appointed to the job for as long as they choose to do it.

As Paul Vixie put it, the root server administrators were “selected by people who are dead now, through processes that are not transparent.” Vixie is president of the Internet Systems Consortium, a non-profit organization that operates the F root server system. Each root server administrator is designated by one of the first 13 letters of the alphabet.

Not every Internet communication requires a root server query because ISPs cache the location of the most popular domain names. Expiration dates are also used, with address information assumed to be current until the expiration date arrives. Even so, the ISC estimates that its system alone handles between 10,000 and 20,000 inquiries per second. Despite that heavy volume — and despite the haphazard nature in which the system was created — the root servers have an excellent performance record. VeriSign claims 100% uptime for its root servers for the last seven years.

“Root server operators tend to shun the spotlight,” Vixie said. “They just want the trains to run on time.”

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