Created By:N.Vedant | Created Date :16 March, 2023
The Domain Name System (DNS) is a hierarchical, distributed naming system for computers, services, and other resources on the Internet or other Internet Protocol (IP) networks. It maps various information to the domain names associated with each of the mapped entities. Most notably, it translates easy-to-remember domain names into the numeric IP addresses needed to locate and identify computer services and devices with the underlying network protocols. The Domain Name System has been an integral part of the functionality of the Internet since 1985.
The Domain Name System delegates responsibility for assigning domain names and associating those names with Internet resources by designating authoritative name servers for each domain. Network administrators can delegate authority over subdomains in their assigned namespace to other nameservers. This mechanism provides a distributed, fault-tolerant service and is designed to avoid a single large central database.
The Internet maintains two main namespaces, the domain name hierarchy and IP address spaces. The Domain Name System manages the hierarchy of domain names and provides translation services between it and the address spaces.
The most common types of records stored in the DNS database are Start of Authority (SOA), IP addresses (A and AAAA), SMTP mail exchangers (MX), name servers (NS), pointers to reverse Lookups from DNS (PTR)., and domain name aliases (CNAME). While not intended as a general-purpose database, DNS has expanded over time to include records of other types of data for automated searches, such as B. DNSSEC entries, or for human queries, such. B. RP (Responsible Person) entries. As a universal database, DNS has also been used to combat unwanted email (spam) by storing a real-time black hole list (RBL).
The Domain Name System originally used the User Datagram Protocol (UDP) as transport over IP. Reliability, security, and privacy issues led to the use of the Transmission Control Protocol (TCP) as well as many other protocol developments.
An analogy often used to explain DNS is that it acts as a phone book for the Internet, translating user-friendly computer hostnames into IP addresses. For example, the hostname www.example.com within the domain name example.com is translated to the addresses 22.214.171.124 (IPv4) and 2606:2800:220:1:248:1893:25c8:1946 (IPv6).
Users take advantage of this when using Uniform Resource Locators (URLs) and email addresses without having to know how the computer actually finds the services.
An important and ubiquitous function of DNS is its pivotal role in distributed Internet services such as cloud services and content delivery networks. When a user accesses a distributed Internet service through a URL, the domain name of the URL is translated to the IP address of a server near the user. The main DNS functionality exploited here is that different users can get different translations for the same domain name at the same time, a key difference from DNS's traditional phone book view. This process of using DNS to assign proxies to users is key to providing faster, more reliable responses on the internet and is widely used by most major internet services.