DNS root servers
Root servers are positioned at the top, or root, of the DNS
hierarchy, and maintain data about each of the top-level zones.
Primary, secondary, and caching-only servers, when first configured, need to know the IP addresses of root servers so that they can begin to resolve client requests about other zones. A default list of root servers is provided in the file /etc/named.root. In addition, you can obtain a current list of root servers by following this procedure: