Besides the distinction between authoritative and local resolution nameservers, there is a distinction within the authoritative nameservers between the "Primary" and "Secondary" nameservers. The primary nameserver is the machine the records are edited and maintained through, and is held to be the final authority on the domain name. If there is an error here, it will propagate throughout the internet, so it is vitally important that the records on the primary nameserver be set up correctly.

These records are stored in something called a "zone file." The zone file is a text file, stored on the nameservers, which contains all the technical information regarding the servers for the domain. All the authoritative nameservers need to have a matching copy of the zone file, since they are equally likely to be asked about the domain whether secondary or primary, though the file is only edited and maintained through the primary nameserver.

The remaining nameserver or nameservers listed on the whois record transfer, or copy, the zone file from the primary nameserver. These nameservers are referred to as secondary, and ensure that the domain does not go off-line if there should happen to be a problem with the primary, and also makes resolution faster by allowing more than one option for finding authoritative information for the domain.