Name server

In short: A name server is a DNS server that holds the binding records for a domain and answers requests about it.

In more detail: At the registrar (the provider where the domain is registered) you enter which name servers are responsible for the domain (NS records). All further records (A, MX, TXT) then live in the DNS zone on those servers.

In Depth

• Several servers: at least two name servers are usual (primary and secondary) so the domain stays resolvable if one fails.
• Changing: if you move the domain to another DNS provider, you change the name servers at the registrar. It can take up to a day until it applies everywhere (caching, TTL).
• Glue records: if the name server itself lives inside the domain, you also need its IP address at the registrar.
• Distinction: a resolver asks on behalf of the user, an authoritative name server gives the final answer for its zone.
• Checking: nslookup -type=ns example.com shows the name servers (nslookup).

See also: DNS, SPF