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The Domain Name System (DNS) is the hierarchical and
decentralized Decentralization or decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or delegated away from a central, authoritative location or group. Concep ...
naming system used to identify computers,
services Service may refer to: Activities :''(See the Religion section for religious activities)'' * Administrative service, a required part of the workload of Faculty (academic staff), university faculty * Civil service, the body of employees of a governm ...
, and other resources reachable through the
internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consist ...

internet
or other
internet protocol The Internet Protocol (IP) is the network layer In the seven-layer OSI model The Open Systems Interconnection model (OSI model) is a conceptual model A conceptual model is a representation of a system, made of the composition of concept C ...
networks. The resource records contained in the DNS associate
domain name A domain name is an identification string String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Film ...
s with other forms of information. These are most commonly used to map human-friendly domain names to the numerical
IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communi ...
es computers need to locate services and devices using the underlying
network protocol A communication protocol is a system of rules that allows two or more entities of a communications system 400px, Communication system A communications system or communication system is a collection of individual telecommunications networ ...
s, but have been extended over time to perform many other functions as well. The Domain Name System has been an essential component of the functionality of the Internet since 1985.


Function

An often-used analogy to explain the Domain Name System is that it serves as the
phone book A telephone directory, commonly called a telephone book, telephone address book, phone book, or the white and yellow pages, is a listing of telephone subscriber The subscription business model is a business model in which a customer must pay ...
for the Internet by translating human-friendly computer
hostname In computer networking, a hostname (archaically nodename) is a label that is assigned to a device connected to a computer network A computer network is a group of computers that use a set of common communication protocols over digital signal ...
s into IP addresses. For example, the domain name www.example.com translates to the addresses (
IPv4 Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol The Internet Protocol (IP) is the network layer communications protocol A communication protocol is a system of rules that allows two or more entities of a ...

IPv4
) and (
IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

IPv6
). The DNS can be quickly and transparently updated, allowing a service's location on the network to change without affecting the end users, who continue to use the same hostname. Users take advantage of this when they use meaningful Uniform Resource Locators (
URL A Uniform Resource Locator (URL), colloquially termed a web address, is a reference to a web resource that specifies its location on a computer network A computer network is a group of computers that use a set of common communication prot ...

URL
s) and
e-mail address An email address identifies an email upThe email_address.html"_;"title="at_sign,_a_part_of_every_SMTP_email_address">at_sign,_a_part_of_every_SMTP_email_address Electronic_mail_(email_or_e-mail)_is_a_method_of_exchanging_messages_("mail ...
es without having to know how the computer actually locates the services. An important and ubiquitous function of the DNS is its central role in distributed Internet services such as
cloud service Cloud computing is the on-demand availability of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operation ...
s and
content delivery network A content delivery network, or content distribution network (CDN), is a geographically distributed network of proxy servers and their data centers. The goal is to provide high availability and performance by distributing the service spatially rel ...
s. When a user accesses a distributed Internet service using a URL, the domain name of the URL is translated to the IP address of a server that is proximal to the user. The key functionality of the DNS exploited here is that different users can ''simultaneously'' receive different translations for the ''same'' domain name, a key point of divergence from a traditional phone-book view of the DNS. This process of using the DNS to assign proximal servers to users is key to providing faster and more reliable responses on the Internet and is widely used by most major Internet services. The DNS reflects the structure of administrative responsibility in the Internet. Each subdomain is a
zone Zone or The Zone may refer to: Places Climate and altitude zones * Death zone (originally the lethal zone), altitudes above a certain point where the amount of oxygen is insufficient to sustain human life for an extended time span * Frigid zone, ...
of administrative autonomy delegated to a manager. For zones operated by a registry, administrative information is often complemented by the registry's RDAP and
WHOIS WHOIS (pronounced as the phrase "who is") is a query and response Communications protocol, protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP addre ...
services. That data can be used to gain insight on, and track responsibility for, a given host on the Internet.


History

Using a simpler, more memorable name in place of a host's numerical address dates back to the
ARPANET The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switching network with distributed control and one of the first networks to implement the Internet protocol suite, TCP/IP protocol suite. Both technologies ...
era. The Stanford Research Institute (now
SRI International SRI International (SRI) is an American nonprofit organization, nonprofit scientific research, scientific research institute and organization headquartered in Menlo Park, California. The trustees of Stanford University established SRI in 1946 as ...
) maintained a text file named HOSTS.TXT that mapped host names to the numerical addresses of computers on the ARPANET.RFC 3467, "Role of the Domain Name System (DNS)", J.C. Klensin, J. Klensin (February 2003).
Elizabeth Feinler Elizabeth Jocelyn "Jake" Feinler (born March 2, 1931) is an American information scientist. From 1972 until 1989 she was director of the Network Information Systems Center at the Stanford Research Institute SRI International (SRI) is an Americ ...
developed and maintained the first ARPANET directory. Maintenance of numerical addresses, called the Assigned Numbers List, was handled by
Jon Postel Jonathan Bruce Postel (; August 6, 1943 – October 16, 1998) was an American computer scientist who made many significant contributions to the development of the Internet, particularly with respect to Internet Standard, standards. He is known p ...

Jon Postel
at the
University of Southern California , mottoeng = "Let whoever earns the palm bear it" , religious_affiliation = Nonsectarian - Methodist Methodism, also called the Methodist movement, is a group of historically related denominations Denomination may refer to: * Religious de ...

University of Southern California
's
Information Sciences Institute The USC Information Sciences Institute (ISI) is a component of the University of Southern California (USC) Viterbi School of Engineering, and specializes in research and development in information processing, computing, and communications techn ...
(ISI), whose team worked closely with SRI. Addresses were assigned manually. Computers, including their hostnames and addresses, were added to the primary file by contacting the SRI
Network Information Center The Network Information Center (NIC), also known as InterNIC from 1993 until 1998, was the organization primarily responsible for Domain Name System The Domain Name System (DNS) is a hierarchical and decentralized naming system for computers ...
(NIC), directed by Feinler, telephone during business hours. Later, Feinler set up a
WHOIS WHOIS (pronounced as the phrase "who is") is a query and response Communications protocol, protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP addre ...
directory on a server in the NIC for retrieval of information about resources, contacts, and entities. She and her team developed the concept of domains. Feinler suggested that domains should be based on the location of the physical address of the computer. Computers at educational institutions would have the domain ''edu'', for example. She and her team managed the Host Naming Registry from 1972 to 1989. By the early 1980s, maintaining a single, centralized host table had become slow and unwieldy and the emerging network required an automated naming system to address technical and personnel issues. Postel directed the task of forging a compromise between five competing proposals of solutions to
Paul Mockapetris Paul V. Mockapetris (born 1948 in Boston Boston (, ), officially the City of Boston, is the and city of the of in the and 21st . The city proper covers with an estimated population of 692,600 in 2019, also making it the most populous c ...
. Mockapetris instead created the Domain Name System in 1983. The
Internet Engineering Task Force The Internet Engineering Task Force (IETF) is an open standards organization, which develops and promotes voluntary Internet standards, in particular the technical standards that comprise the Internet protocol suite (TCP/IP). It has no formal ...
published the original specifications in RFC 882 and RFC 883 in November 1983. In 1984, four
UC Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public In public relations and communication science, publics are groups of individual people, and the public (a.k.a. the general public) is the tota ...

UC Berkeley
students, Douglas Terry, Mark Painter, David Riggle, and Songnian Zhou, wrote the first
Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser Multi-user software is computer software Software is a collection of Instruction (computer science), instructions that tell a computer how to work. This is in contrast t ...

Unix
name server implementation for the Berkeley Internet Name Domain, commonly referred to as
BIND BIND (), or named (pronounced ''name-dee'': , short for ''name daemon Daemon is the Latin word for the Ancient Greek daimon (δαίμων: "god", "godlike", "power", "fate"), which originally referred to a lesser deity or guiding spirit such a ...
. In 1985, Kevin Dunlap of DEC substantially revised the DNS implementation. Mike Karels, Phil Almquist, and
Paul Vixie Paul Vixie is an American computer scientist A computer scientist is a person A person (plural people or persons) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a ...
have maintained BIND since then. In the early 1990s, BIND was
ported In , porting is the process of adapting for the purpose of achieving some form of execution in a that is different from the one that a given program (meant for such execution) was originally designed for (e.g., different , operating system, or ...
to the
Windows NT Windows NT is a proprietary {{Short pages monitor * Alternative DNS root * Comparison of DNS server software * Domain hijacking *
DNS hijacking DNS hijacking, DNS poisoning, or DNS redirection is the practice of subverting the resolution of Domain Name System (DNS) queries. This can be achieved by malware that overrides a computer's TCP/IP configuration to point at a rogue DNS server und ...
* DNS management software * DNS over HTTPS * DNS over TLS * Hierarchical namespace * IPv6 brokenness and DNS whitelisting * Multicast DNS * Public recursive name server * resolv.conf * Split-horizon DNS * List of DNS record types * List of managed DNS providers * Zone file * DNS leak


References


Sources

*


External links

*
Zytrax.com
Open Source Guide – DNS for Rocket Scientists.
Internet Governance and the Domain Name System: Issues for Congress
Congressional Research Service * {{Authority control Computer-related introductions in 1983 Domain Name System, Application layer protocols Internet Standards