Editing Domain Name System (section)

{{Short description|System to identify resources on a network}}
{{redirect|DNS}}
{{Use American English|date = February 2019}}
{{Infobox networking protocol
| title        = Domain Name Service
| logo         = 
| logo alt     = 
| image        = 
| image alt    = 
| caption      = 
| is stack     = 
| abbreviation = DNS
| purpose      = To identify resources on networks
| developer    =[[Paul Mockapetris]]
| date         = {{Start date and age|1983|11|  }}
| based on     = 
| influenced   = 
| osilayer     = [[Application layer]]
| ports        = 53
| rfcs         = RFC 1034, RFC 1035
| hardware     = 
}}
{{IPstack}}
{{Internet history timeline}}

The '''Domain Name System''' ('''DNS''') is a hierarchical and distributed [[name service]] that provides a naming system for [[computer]]s, services, and other resources on the Internet or other [[Internet Protocol]] (IP) networks. It associates various information with ''[[domain name]]s'' ([[identification (information)|identification]] [[String (computer science)|strings]]) assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical [[IP address]]es needed for locating and identifying computer services and devices with the underlying [[network protocol]]s.<ref>{{Cite journal |last1=Wu |first1=Hao |last2=Dang |first2=Xianglei |last3=Wang |first3=Lidong |last4=He |first4=Longtao |date=2016 |title=Information fusion-based method for distributed domain name system cache poisoning attack detection and identification |url=https://onlinelibrary.wiley.com/doi/10.1049/iet-ifs.2014.0386 |journal=IET Information Security |language=en |volume=10 |issue=1 |pages=37–44 |doi=10.1049/iet-ifs.2014.0386 |s2cid=45091791 |issn=1751-8717|url-access=subscription }}</ref> The Domain Name System has been an essential component of the functionality of the Internet since 1985.

The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating [[authoritative name server]]s for each domain. Network administrators may delegate authority over [[subdomain]]s of their allocated name space to other name servers. This mechanism provides distributed and [[fault-tolerant]] service and was designed to avoid a single large central database. In addition, the DNS specifies the technical functionality of the [[Database model|database]] service that is at its core. It defines the DNS protocol, a detailed specification of the data structures and [[data communication]] exchanges used in the DNS, as part of the [[Internet protocol suite]].

The Internet maintains two principal [[namespace]]s, the domain name hierarchy and the IP [[address space]]s.{{Ref RFC|791}} The Domain Name System maintains the domain name hierarchy and provides translation services between it and the address spaces. Internet name servers and a [[communication protocol]] implement the Domain Name System. A DNS name server is a server that stores the DNS records for a domain; a DNS name server responds with answers to queries against its database.

The most common types of records stored in the DNS database are for start of authority ([[SOA record|SOA]]), IP addresses ([[List of DNS record types#A|A]] and [[AAAA record|AAAA]]), [[SMTP]] [[mail exchanger]]s (MX), name servers (NS), pointers for [[reverse DNS lookup]]s (PTR), and [[domain name alias]]es (CNAME). Although not intended to be a general-purpose database, DNS has been expanded over time to store records for other types of data for either automatic lookups, such as [[DNSSEC]] records, or for human queries such as ''responsible person'' (RP) records. As a general-purpose database, the DNS has also been used in combating [[unsolicited email]] (spam) by storing [[Domain Name System blocklist|blocklists]]. The DNS database is conventionally stored in a structured text file, the [[zone file]], but other database systems are common.

The Domain Name System originally used the [[User Datagram Protocol]] (UDP) as transport over IP. Reliability, security, and privacy concerns spawned the use of the [[Transmission Control Protocol]] (TCP) as well as numerous other protocol developments.