Editing Domain Name System (section)

===Name servers===
The Domain Name System is maintained by a [[distributed database]] system, which uses the [[client–server model]]. The nodes of this database are the [[name server]]s. Each domain has at least one authoritative DNS server that publishes information about that domain and the name servers of any domains subordinate to it. The top of the hierarchy is served by the [[root name server]]s, the servers to query when looking up (''resolving'') a [[Top-level domain|TLD]].

====Authoritative name server====
An ''authoritative'' name server is a name server that only gives [[Name server#Authoritative answer|answers]] to DNS queries from data that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers obtained via a query to another name server that only maintains a cache of data.

An authoritative name server can either be a ''primary'' server or a ''secondary'' server. Historically the terms [[Master/slave (technology)|''master/slave'']] and ''primary/secondary'' were sometimes used interchangeably<ref>{{Cite journal|last1=Fujiwara|first1=Kazunori|last2=Sullivan|first2=Andrew|last3=Hoffman|first3=Paul|title=DNS Terminology|url=https://www.rfc-editor.org/rfc/rfc9499.html#section-6-4.42|access-date=2024-07-01|website=tools.ietf.org|year=2024 |doi=10.17487/RFC9499 |language=en|url-access=subscription}}</ref> but the current practice is to use the latter form. A primary server is a server that stores the original copies of all zone records. A secondary server uses a special [[AXFR|automatic updating mechanism]] in the DNS protocol in communication with its primary to maintain an identical copy of the primary records.

Every DNS zone must be assigned a set of authoritative name servers. This set of servers is stored in the parent domain zone with name server (NS) records.

An authoritative server indicates its status of supplying definitive answers, deemed ''authoritative'', by setting a protocol flag, called the "''Authoritative Answer''" (''AA'') [[bit]] in its responses.<ref name="rfc1035" /> This flag is usually reproduced prominently in the output of DNS administration query tools, such as [[Domain Information Groper|dig]], to indicate ''that the responding name server is an authority for the domain name in question.''<ref name="rfc1035" />

When a name server is designated as the authoritative server for a domain name for which it does not have authoritative data, it presents a type of error called a "lame delegation" or "lame response".<ref>{{Cite book|last1=Nemeth|first1=Evi|url=https://books.google.com/books?id=GB_O89fnz_sC&dq=%22lame+delegation%22&pg=PA475|title=Linux Administration Handbook|last2=Snyder|first2=Garth|last3=Hein|first3=Trent R.|date=2006-10-30|publisher=Addison-Wesley Professional|isbn=978-0-13-700275-7|language=en}}</ref><ref>{{Cite book|last1=Bissyande|first1=Tegawendé F.|url=https://books.google.com/books?id=YjE5DwAAQBAJ&dq=%22lame+delegation%22&pg=PA235|title=e-Infrastructure and e-Services for Developing Countries: 8th International Conference, AFRICOMM 2016, Ouagadougou, Burkina Faso, December 6-7, 2016, Proceedings|last2=Sie|first2=Oumarou|date=2017-10-09|publisher=Springer|isbn=978-3-319-66742-3|language=en}}</ref>