Authoritative nameserver

An authoritative nameserver (alternatively spelled, authoritative name server; also known as authoritative domain server; hereinafter, the Server) is any nameserver that provides its DNS zone with definitive DNS name resolution based on the data that is stored within this Server. The Servers can be primary nameservers (alternatively known as "master nameservers") or secondary nameservers (or "slave nameservers").

Some nameservers can also perform more than just the Server. They can function as recursive nameservers, while caching DNS records.