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A DNS root zone is the top level of the DNS hierarchy for a given DNS system. The term, when not otherwise qualified, is generally used to refer to the root zone of the largest global DNS system deployed on the Internet. This "official" DNS system is by far the largest deployment of DNS in the world. The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. ...
The combination of limits in the DNS and IP protocols means that there is a limit of thirteen root server names that can be accommodated within a root zone. The AMS-IX mirror of the K root-server. ...
Parent zones
Responsible for defining its points of delegation (sub-zones), ensuring the availability of a server to respond with the appropriate referrals (NS records) for those sub-zones, updating the referral information upon request from the child sub-zone in a timely fashion, and ensuring the child honors its responsibilites.
Technical details of root server lookup There are thirteen root server names that are authoritative for queries to the global DNS root zone, the maximum number possible. The root servers hold the list of addresses for the authoritative servers for the top-level domains. Every name lookup must either start with an access to a root server, or use information that was once obtained from a root server. A top-level domain (TLD) is the last part of an Internet domain name; that is, the letters which follow the final dot of any domain name. ...
The root servers have the official names a.root-servers.net to m.root-servers.net. However, to look up the IP address of a root server from these names, you must first be able to look up a root server, to find the address of an authoritative server for the .net DNS zone. Clearly this creates a paradox, so the address of at least one root server needs to be known by a host in order to bootstrap access to the DNS system. This is usually done by shipping the addresses of all known root DNS servers as a file with the computer operating system: the IP addresses of some root servers will change over the years, but only one correct address is needed for the lookup process to complete. This file is called named.cache when distributed with the BIND nameserver. Bootstrapping alludes to a German legend about a Baron Münchhausen, who was able to lift himself out of a swamp by pulling himself up by his bootstraps. ...
Once the address of a single functioning root server is known, the rest of the DNS information can be discovered recursively, and the address of any machine on the Internet can be looked up in this way.
An additional level of redundancy is provided by the fact that a single root server name, and its corresponding IP address, may correspond with many physical servers around the world, using a method called anycast. Anycast is a network addressing and routing scheme whereby data is routed to the nearest or best destination as viewed by the routing topology. ...
Redundancy and diversity The root DNS servers are essential to the function of the Internet, as so many protocols use DNS, either directly or indirectly. They are potentially points of failure for the entire Internet. For this reason, there are 13 named root servers worldwide. There are not more root servers because a single DNS reply can only be 512 bytes long; while it is possible to fit 15 root servers in a datagram of this size, the variable size of DNS packets makes it prudent to only have 13 root servers.
They are housed in multiple sites with high bandwidth access, to try to prevent attacks such as distributed denial-of-service attacks. Most of these single-site installations are still in the United States. Usually each DNS server in a given site is actually a cluster of servers behind a load-balancing set of routers. This article or section is in need of attention from an expert on the subject. ...
However, a number of root servers lie outside the United States:
The modern trend is to use anycast to give resilience and to balance load across a wide geographic area. For example, j.root-servers.net, f.root-servers.net and k.root-servers.net are served using anycast from a number of sites worldwide. The use of anycast has allowed the growth of non-U.S. root DNS servers until most DNS root instances are outside the U.S. Stockholm panorama from the City Hall is the capital of Sweden, and consequently the site of its Government and Parliament as well as the residence of the Swedish head of state, King Carl XVI Gustaf. ...
Anycast is a network addressing and routing scheme whereby data is routed to the nearest or best destination as viewed by the routing topology. ...
Amsterdam Location Flag Country Netherlands Province North Holland Population 742,951(1 January 2005) Demonym Amsterdammer Coordinates Website www. ...
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Tokyo , literally eastern capital) is the capital of Japan and one of the 47 prefectures of Japan. ...
Tokyo , literally eastern capital) is the capital of Japan and one of the 47 prefectures of Japan. ...
City flag City coat of arms Motto: Fluctuat nec mergitur Tossed by the waves, she does not founder Coordinates : , Time Zone : CET (GMT +1) Administration Subdivisions 20 arrondissements Département Paris (75) Région Île-de-France Mayor Bertrand Delanoë (PS) City (commune) Characteristics Land Area 86. ...
Seoul (SÅul|서울) ) is the capital and largest city of South Korea (Republic of Korea). ...
Anycast is a network addressing and routing scheme whereby data is routed to the nearest or best destination as viewed by the routing topology. ...
Anycast is a network addressing and routing scheme whereby data is routed to the nearest or best destination as viewed by the routing topology. ...
Details of all the root servers can be seen at the root-servers.org website.
See also The AS112 project is a group of volunteer-administered name server operators, who run an anycast instance of name servers that answer for the RFC 1918 reverse DNS networks, and the reverse address space of link-local RFC 3330 and RFC 3927 networks. ...
In addition to the Internets main DNS root (currently consisting of 13 nominal root nameservers working in agreement with ICANN), several organizations operate alternative DNS roots (often referred to as alt roots). ...
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