Editing Name server (section)

===Authoritative name server===
An authoritative name server is a name server that is responsible for giving [[#Authoritative answer|answers]] in response to questions asked about names in a [[DNS zone|zone]]. An authoritative-only name server returns answers only to queries about domain names for which it is responsible (as  specifically configured by its administrator). 

An authoritative name server can either be a ''primary'' server or a ''secondary'' server. A primary server for a zone is the server that stores the definitive versions of all records in that zone.  It is identified in the start-of-authority (SOA) resource record.  A secondary server for a zone uses an automatic updating mechanism to maintain an identical copy of the primary server's database for a zone. Examples of such mechanisms include [[DNS zone transfer]]s and file transfer protocols. DNS provides a mechanism whereby the primary for a zone can notify all the known secondaries for that zone when the contents of the zone have changed. The contents of a zone are either manually configured by an administrator, or managed using [[Dynamic DNS]].<ref>{{cite IETF |title=Dynamic Updates in the Domain Name System (DNS Update) |rfc=2136 |author1=Yakov Rekhter |author2=Susan Thomson |author3=Jim Bound |author4=Paul Vixie |date=April 1007 |publisher=[[Internet Engineering Task Force|IETF]] |access-date=17 December 2015 }}</ref>

Every domain name appears in a zone served by one or more authoritative name servers. The [[fully qualified domain name]]s of the authoritative name servers of a zone are listed in the NS records of that zone. If the server for a zone is not also authoritative for its parent zone, the server for the parent zone must be configured with a [[glue record|delegation]] for the zone.<ref>{{cite IETF |title=Clarifications to the DNS Specification |rfc=2181 |author1=Robert Elz |author2=Randy Bush |date=July 1997 |publisher=[[Internet Engineering Task Force|IETF]] |access-date=17 December 2015 }}</ref>

When a domain is registered with a [[domain name registrar]], the zone administrator provides the list of name servers (typically at least two, for redundancy<ref name="techterms">{{cite web|title=Name Server definition at techterms.com|url=http://www.techterms.com/definition/nameserver}}</ref>) that are authoritative for the zone that contains the domain. The registrar provides the names of these servers to the [[domain registry]] for the [[top level domain|top-level domain]] containing the zone. The domain registry in turn configures the authoritative name servers for that top-level domain with delegations for each server for the zone. If the fully qualified domain name of any name server for a zone appears within that zone, the zone administrator provides IP addresses for that name server, which are installed in the parent zone as [[glue records]]; otherwise, the delegation consists of the list of NS records for that zone.<ref>{{cite IETF |title=Domain Names - Domain Concepts and Facilities |rfc=1034 |sectionname=Technical considerations |section=4.2.1 |author1=Paul Mockapetris |date=November 1987 |publisher=[[Internet Engineering Task Force|IETF]] |access-date=17 December 2015 }}
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====Authoritative answer====<!-- 'Authoritative Answer' redirects here -->
A name server indicates that its response is authoritative by setting the ''Authoritative Answer'' (''AA'') bit in the response to a query on a name for which it is authoritative. Name servers providing answers for which they are not authoritative (for example, name servers for parent zones) do not set the ''AA'' bit.<ref name="rfc1035 "/>