root server

A machine that has the software and data needed to locate authoritative data for the top-level domains in the Domain Name System (DNS) hierarchy. In other words, root servers know which name servers contain authoritative data for .com, .net, .fr, .uk, and so on. Root servers are in fact a special kind of name server. Currently, technical specifications limit the number of root servers to thirteen. These machines are located around the globe-in the U.S., the U.K., Sweden, and Japan.