A DNS Server is a computer that completes the process of name resolution in DNS. DNS Servers contain files, called zone files, that enable them to resolve names to IP addresses (or vice versa). When queried, a DNS Server responds in one of three ways:
- The server returns the requested name-resolution or IP-resolution information.
- The server returns a pointer to another DNS Server that can service the request.
- The server indicates that it does not have the requested information.
DNS Servers might, during the course of preparing to return the requested resolution information, query other DNS Servers. But beyond that, DNS Servers do not perform any operations other than those mentioned in the previous list.
There are three main kinds of DNS Servers — primary servers, secondary servers, and caching servers.