, a name server
(also called 'nameserver') consists of a program or computer server
that implements a name-service protocol
. It will normally map
(i.e. connect) a human-recognisable
identifier of a host
(for example, the domain name
'en.wikipedia.org') to its computer-recognisable
identifier (such as the Internet Protocol
18.104.22.168), and vice versa.
Domain Name System
Internet name servers implement the Domain Name System
(DNS) protocol. Name servers also exist on some Microsoft Windows
networks where one host can take the role of NetBIOS
Master Browser and act as a NBNS
server. Small local networks
of Windows systems require no central name server, and generally perform name-resolution using broadcasts
A domain name server is a server that governs the DNS records, such as ARECORD (Host), CNAMES (Aliases), and MX (Mail Exchange) for a domain name.
Primary and secondary nameservers
Every domain name must have a primary nameserver (eg. ns1.domainname.com), and at least one secondary nameserver (ns2.domainname.com etc). This requirement aims to make the domain still reachable even if one nameserver becomes inaccessible.
Authoritative name server
An authoritative name server
is a name server that can give an authoritative answer
to a DNS query, and not just a cached answer that was given by another name server. All primary and secondary name servers give authoritative answers, as can certain other "shadow" name servers.