A DNS root zone is the top-level DNS zone The DNS namespace is defined by RFC 1034, "Domain Names - Concepts and Facilities" and RFC 1035, "Domain Names - Implementation and Specification". It is divided in hierarchical tree-like fashion into cascading lower-level domains that are ordered as a reverse-prioritized concatenation of names, each level separated by a full in a Domain Name System The Domain Name System is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers (DNS) hierarchy. Most commonly it refers to the root zone of the largest global DNS, deployed for the Internet The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and. The zone is managed by the Internet Assigned Numbers Authority The Internet Assigned Numbers Authority is the entity that oversees global IP address allocation, root zone management for the Domain Name System (DNS), media types, and other Internet Protocol related assignments. It is operated by the Internet Corporation for Assigned Names and Numbers, better known as ICANN (IANA), managed by ICANN The Internet Corporation for Assigned Names and Numbers is a non-profit corporation headquartered in Marina del Rey, California, United States that was created on September 18, 1998, and incorporated on September 30, 1998 to be able to oversee a number of Internet-related tasks previously performed directly on behalf of the U.S. government by.
A combination of limits in the DNS and certain protocols, namely the practical size of unfragmented User Datagram Protocol The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network without requiring prior communications to set up special transmission (UDP) packets, resulted in a limited number of root server A root name server is a name server for the Domain Name System's root zone. It directly answers requests for records in the root zone and answers other requests returning a list of the designated authoritative name servers for the appropriate top-level domain . The root name servers are a critical part of the Internet because they are the first addresses that can be accommodated in DNS name query responses. This limit has determined the number of name server installations at (currently) 13 clusters, serving the needs of the entire public Internet worldwide.
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Initialization of DNS service
There are thirteen root server clusters that are authoritative for queries to the global DNS root zone. The root servers hold the lists of names and addresses for the authoritative servers for all of the top-level domains A top-level domain is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last label of a fully qualified domain name. For example, in the. Every name lookup must either start with a query to a root server or use information that was once obtained from a root server.
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, a DNS resolver 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 must be known by a host in order to bootstrap In computing, bootstrapping is a technique by which a simple computer program activates a more complicated system of programs. In the start up process of a computer system, a small program such as BIOS, initializes and tests the hardware, peripherals and external memory devices are connected, then loads a program from one of them and passes access to the DNS. This is usually done by shipping the addresses of all known DNS root 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 resolver to obtain the current list of name servers. This file is called named.cache in the BIND nameserver reference implementation and a current version is officially distributed by ICANN The Internet Corporation for Assigned Names and Numbers is a non-profit corporation headquartered in Marina del Rey, California, United States that was created on September 18, 1998, and incorporated on September 30, 1998 to be able to oversee a number of Internet-related tasks previously performed directly on behalf of the U.S. government by's InterNIC The Internet Network Information Center, known as InterNIC, was the Internet governing body primarily responsible for domain name and IP address allocations until September 18, 1998 when this role was assumed by the Internet Corporation for Assigned Names and Numbers . It was accessed through the domain name internic.net, with email, FTP and World.[1]
Once the address of a single functioning root server is known, all other DNS information can be discovered recursively, and the address of any domain name may be found.
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 electronic mail, are based on domain names. The DNS servers are potential points of failure for the entire Internet. For this reason, there are multiple root servers worldwide. The number has been limited to 13 in DNS responses because DNS was limited to 512-byte packets until protocol extensions (EDNS Extension mechanisms for DNS is a specification for expanding the size of several parameters of the Domain Name System (DNS) protocol which had size restrictions that the Internet engineering community deemed too limited for increasing functionality of the protocol. The first set of extensions was published in 1999 by the Internet Engineering Task) were designed to lift this restriction. While it is possible to fit more entries into a packet of this size when using "label compression", 13 was chosen as a reliable limit. Since the advent of IPv6 Internet Protocol version 6 is a version of the Internet Protocol that is designed to succeed IPv4, the first publicly used implementation, which is still in dominant use currently[update]. It is an Internet Layer protocol for packet-switched internetworks. The main driving force for the redesign of Internet Protocol is the foreseeable IPv4, the next generation IP address An Internet Protocol address is a numerical label that is assigned to devices participating in a computer network, that uses the Internet Protocol for communication between its nodes. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A structure, previous practices are being modified and extra space is filled with IPv6 name servers.
The root name servers are hosted in multiple secure sites with high-bandwidth access to accommodate the traffic load. Initially all of these installations were located in the United States. However, the distribution has shifted and this is no longer the case. Usually each DNS server installation at a given site is physically a cluster of machines with load-balancing routers. A comprehensive list of servers, their locations, and properties is available at http://root-servers.org.
The modern trend is to use anycast Anycast is a network addressing and routing methodology in which datagrams from a single sender are routed to the topologically nearest node in a group of potential receivers all identified by the same destination address addressing and routing to provide resilience and load balancing across a wide geographic area. For example, the j.root-servers.net root server, maintained by VeriSign VeriSign, Inc. is an American company based in Mountain View, CA that operates a diverse array of network infrastructure, including two of the Internet's thirteen root nameservers, the generic top-level domains for .com, .net, .cc, .name and .tv. VeriSign also provides a variety of security services ranging from digital certificates, and managed, is represented by 41 (as of July 2008[update]) individual server systems located around the world which can be queried using anycast addressing.[citation needed]
See also
- Alternative DNS roots The Internet uses the Domain Name System to associate the names of computers with their numeric IP addresses and with other information. The top level of the domain name hierarchy, the DNS root, contains the top-level domains that appear as the suffixes of all Internet domain names. The official DNS root is administered by the Internet Corporation
- AS112 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 5735 and RFC 3927 networks
- Internet backbone The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet. These data routes are hosted by commercial, government, academic and other high-capacity network centers, the Internet exchange points and network access points, that interchange Internet traffic between
References
- ^ Internic.net, Official named.cache distribution
- RFC 2870 - Root Name Server Operational Requirements
- RFC 2826 - IAB Technical Comment on the Unique DNS Root
External links
- Root-servers.org
- CircleID.com, on DNS Root Servers
- CAIDA.org, paper on root server location problem
- CirlceID.com, More root server instances outside the U.S. than inside
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Tue, 24 Aug 2010 08:46:45 GMT+00:00
tweakers.net Over enkele weken wordt de publieke sleutel van de .nl-zone gepubliceerd in de root -zone van het internet; vanaf dan kunnen dns -resolvers met ondersteuning ... SIDN heeft DNSSEC voor .nl-zone succesvol ingevoerd Ezpress (persbericht)
