Domain Name System

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The Domain Name[1] System (DNS) is an essential component of the internet[2]’s framework. It acts as an interpreter between user-friendly hostnames and numeric IP addresses, facilitating swift and efficient access to websites and digital services. The DNS, which originated as a straightforward mapping system during the ARPANET era, has evolved into a sophisticated hierarchical structure indispensable for cloud services and content delivery networks. Protocols such as UDP and TCP are utilized by the DNS to ensure reliable, secure, and private connections. It also maintains a variety of record types, including SOA, A, AAAA, MX, NS, PTR, and CNAME, traditionally housed in a zone file. These records are vital for the functioning of distributed Internet services. The DNS enhances user experience by allocating nearby servers for quicker responses. Its structure mirrors the internet’s administrative responsibility, with autonomous zones delegated to managers for each subdomain.

Terms definitions
1. Domain name ( Domain Name ) Domain names are textual identifiers that signify internet resources, including computers and services. They symbolize ownership or control of a resource and offer a memorable name for these entities. The structure of a domain name consists of labels concatenated and separated by dots, arranged in a hierarchy from right to left. Each label can hold 1 to 63 octets, and the total domain name should not go beyond 253 ASCII characters. The Domain Name System (DNS) converts these domain names into IP addresses, aiding in the distribution of web traffic among various servers. Organized in a tree structure, domain names have Top-Level Domains (TLDs) like .com, .org, .net at the topmost level. The Internet Corporation for Assigned Names and Numbers (ICANN) manages the allocation of TLDs and accredits domain registrars. Domain names can also be internationalized, with numerous registries adopting the Internationalized domain name (IDNA) system approved by ICANN. The domain name sector is vulnerable to cyber threats such as spoofing, but protective measures are in place.
2. internet. The Internet, a global network of interconnected computer systems, utilizes standardized communication protocols, predominantly TCP/IP, to connect devices across the globe. The term 'Internet' has its roots in the 1849 term 'internetted' and was later adopted by the US War Department in 1945. The inception of the Internet can be traced back to the 1960s when computer scientists developed time-sharing systems, which eventually led to the creation of ARPANET in 1969. The Internet operates autonomously, without any central control, and the Internet Corporation for Assigned Names and Numbers (ICANN) manages its primary name spaces. It has revolutionized traditional communication methods and has seen an exponential growth, with the number of internet users growing by 20% to 50% every year. In 2019, more than half of the global population was using the Internet. The Internet protocol suite, comprising TCP/IP and four conceptual layers, directs internet packets to their intended destinations. Fundamental services such as email and Internet telephony function on the Internet. The World Wide Web, an extensive network of interconnected documents, serves as a crucial element of the Internet.
Domain Name System (Wikipedia)

The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names (identification strings) assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. 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 servers for each domain. Network administrators may delegate authority over subdomains 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 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 namespaces, the domain name hierarchy and the IP address spaces. 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), IP addresses (A and AAAA), SMTP mail exchangers (MX), name servers (NS), pointers for reverse DNS lookups (PTR), and domain name aliases (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 a real-time blackhole list (RBL). The DNS database is traditionally 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.

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