Authoritative DNS

Authoritative DNS is the type of DNS that controls the DNS records for a particular domain. For instance, for sagonet.com the authoritative DNS servers are ns1.sagonet.com and ns2.sagonet.com. They only respond to domains they are in charge of.

Contrast this with Recursive DNS where those servers will give you and answer for any thing. (Google.com, Sagonet.com, AdventuresInLinux.tv...)