Editing Root name server (section)

{{Short description|Name server for the DNS root zone}}
{{Use American English|date=January 2019}}
{{Use dmy dates|date=January 2020}}
[[File:ams-ix.k.root-servers.net.jpg|290px|thumb|A [[Cisco]] 7301 router and a [[Juniper Networks|Juniper]] M7i, part of the K root-server instance at [[Amsterdam Internet Exchange|AMS-IX]]]]
A '''root name server''' is a [[name server]] for the [[DNS root zone|root zone]] of the [[Domain Name System]] (DNS) of the [[Internet]]. It directly answers requests for records in the root zone and answers other requests by returning a list of the [[authoritative name server]]s for the appropriate [[top-level domain]] (TLD). The root name servers are a critical part of the Internet infrastructure because they are the first step in [[Resolver (DNS)|resolving]] human-readable host names into [[IP address]]es that are used in communication between [[host (network)|Internet hosts]].

A combination of limits in the DNS and certain protocols, namely the practical size of unfragmented [[User Datagram Protocol]] (UDP) packets, resulted in a decision to limit the number of root servers to thirteen server addresses.<ref>{{cite mailing list |url=https://lists.isc.org/pipermail/bind-users/2011-November/085653.html |title=Reason for Limited number of Root DNS Servers |date=11 November 2011 |access-date=8 January 2016 |mailing-list=bind-users |author=Mark Andrews, [[Internet Systems Consortium|ISC]] }}</ref><ref>{{cite web|url=https://www.netnod.se/dns/dns-root-server-faq|title=DNS root server FAQ|publisher=[[Netnod]]|access-date=18 January 2016}}</ref> The use of [[anycast]] addressing permits the actual number of root server instances to be much larger, and is 1,733 {{as of|2024|03|04|lc=on|df=US}}.<ref name="root-servers-org">{{cite web|url=https://root-servers.org/|title=root-servers.org|access-date=4 March 2024}}</ref>