Editing DNS root zone (section)

==Redundancy and diversity==
The root DNS servers are essential to the function of the Internet, as most Internet services, such as the [[World Wide Web]] and email, are based on domain names. The DNS servers are potential points of failure for the entire Internet. For this reason, multiple root servers are distributed worldwide.<ref name=SANS>{{cite web|title=SANS Institute InfoSec Reading Room|publisher=SANS|url=http://www.sans.org/reading-room/whitepapers/dns/secure-root-dns-servers-991|access-date=March 17, 2014}}</ref> The DNS packet size of 512 octets limits a DNS response to thirteen addresses, until protocol extensions ([[Extension Mechanisms for DNS|see Extension Mechanisms for DNS]]) lifted this restriction.<ref name=about>{{cite web|title=Why There Are Only 13 DNS Root Name Servers|author=Bradley Mitchell|date=November 19, 2008|publisher=[[About.com]]|url=http://compnetworking.about.com/b/2008/11/19/why-there-are-only-13-dns-root-name-servers.htm|access-date=March 17, 2014|archive-date=March 18, 2014|archive-url=https://web.archive.org/web/20140318020048/http://compnetworking.about.com/b/2008/11/19/why-there-are-only-13-dns-root-name-servers.htm|url-status=dead}}</ref> While it is possible to fit more entries into a packet of this size when using label compression, thirteen was chosen as a reliable limit. Since the introduction of [[IPv6]], the successor [[Internet Protocol]] to [[IPv4]], previous practices are being modified and extra space is filled with IPv6 name servers.

The [[root name server]]s are hosted in multiple secure sites with high-bandwidth access to accommodate the traffic load. At first, all of these installations were located in the United States; however, the distribution has shifted and this is no longer the case.<ref>{{cite web|title=DNS Root Servers: The most critical infrastructure on the internet|date=November 15, 2013|publisher=Slash Root|url=http://www.slashroot.in/dns-root-servers-most-critical-infrastructure-internet}}</ref> Usually each DNS server installation at a given site is a cluster of computers with load-balancing routers.<ref name=about /> A comprehensive list of servers, their locations, and properties is available at https://root-servers.org/. {{as of|2023|6|24}}, there were 1708 root servers worldwide.<ref>{{cite web|title=Root Servers Technical Operations Assn|url=http://root-servers.org/|access-date=June 29, 2023|archive-url=https://web.archive.org/web/20230624010603/https://root-servers.org/|archive-date=June 24, 2023|url-status=dead}}</ref>

The modern trend is to use [[anycast]] addressing and routing to provide resilience and load balancing across a wide geographic area. For example, the ''j.root-servers.net'' server, maintained by [[Verisign]], is represented by 104 ({{as of|2016|1|lc=on}}) individual server systems located around the world, which can be queried using anycast addressing.<ref>{{cite web|title=Root Server Technical Operations Assn|url=https://root-servers.org/}}</ref>