Domain Name System

Domain name space

Domain Name System (DNS) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most importantly, it translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. By providing a worldwide, distributed directory service, the Domain Name System is an essential component of the functionality of the Internet.

History

The DNS was created in 1983 by Paul Mockapetris and Jon Postel. The original specifications were published in RFC 882 and RFC 883, which were later superseded by RFC 1034 and RFC 1035.

Structure

The Domain Name System is organized in a hierarchical structure. At the top of the hierarchy is the root name server, followed by top-level domains (TLDs) such as .com, .org, and .net. Below the TLDs are second-level domains and further lower-level domains.

Root Name Servers

The root name servers are a critical part of the DNS. They are responsible for the root zone, which is the top-level DNS zone in the hierarchical namespace of the Domain Name System.

Top-Level Domains (TLDs)

TLDs are the highest level of domain names in the DNS hierarchy. They are divided into two main categories: generic top-level domains (gTLDs) and country code top-level domains (ccTLDs).

Second-Level Domains

Second-level domains are directly below TLDs in the DNS hierarchy. They are often used to represent specific organizations or entities.

Functionality

The primary function of the DNS is to translate domain names into IP addresses. This process is known as name resolution. When a user enters a domain name into a web browser, the DNS resolver queries the DNS servers to find the corresponding IP address.

DNS Records

DNS records are used to store information about domain names. Common types of DNS records include:

• A record: Maps a domain name to an IPv4 address.
• AAAA record: Maps a domain name to an IPv6 address.
• CNAME record: Maps a domain name to another domain name.
• MX record: Specifies the mail servers for a domain.
• TXT record: Contains text information for various purposes.

Security

DNS security is a critical aspect of the system. DNSSEC (Domain Name System Security Extensions) is a suite of specifications used to secure information provided by the DNS. It is designed to protect against attacks such as cache poisoning and man-in-the-middle attacks.

Related Pages

• Internet
• IP address
• Root name server
• Top-level domain
• Generic top-level domain
• Country code top-level domain
• DNSSEC
• Cache poisoning
• Man-in-the-middle attack