Domain Name System (DNS) is a protocol for exchanging data on the Internet; a hierarchical and decentralized naming system for computers and other devices connected to the internet or a private network . DNS is used as the medium to translate domain names to their respective IP addresses when a client initiates a request query. It translates the domain names to the numerical IP addresses needed to locate and identify the computer services and devices with the underlying network protocols. For example, when we want to visit a website, we turn on the computer, open a web browser, and type in the domain name we want to visit, e.g. facebook.com; the DNS then translates the name (facebook.com) into an IP address. By providing worldwide distributed directory service and storing the database of all the domain names and their IP addresses which are registered on the network, DNS has become an essential entity to the functionality of the Internet since 1985. DNS can be defined as an attendance register for various websites present over the internet. It maintains the database of all the websites Domain Names and their IP addresses that are operational all over the world.
DNS delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. It delegates authority over sub-domains of their allocated name space to other name servers. It also specifies the technical functionality of the database service that is at its core. As a part of the Internet Protocol Suite, DNS defines a detailed specification of the data structures and data communication exchanges used in the DNS.
The Internet maintains the domain name hierarchy and the Internet Protocol (IP) address spaces as its two principal namespaces. It maintains the domain name hierarchy to provide translation services between itself and the address spaces. A DNS name server is a server that stores the DNS records for a domain; it responds with answers to queries against its database. For example, the domain name www.anything.com can be translated into the addresses 18.104.22.168 (IPv4) and 2606:2800:220:1:248:1893:25c8:1946 (IPv6). The DNS enables quick and transparent update, allowing a service’s location on the network to change without affecting the end users, who uses the same hostname.
A central role in distributed Internet services such as cloud services and content delivery networks is one very important and ubiquitous function of DNS. In a distributed Internet service, when a user accesses a URL, the DNS translates the domain name of the URL into the IP address of a server that is proximal to the user. A key functionality of DNS is that the different users can simultaneously receive different translations for the same domain name. The DNS provides faster and more reliable responses on the Internet and is widely used by most major Internet services.
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