The Domain Name System (DNS) is a
hierarchical distributed naming system for computers, services, or any resource
connected to the
Internet
or a
private
network. It associates various information with
domain names assigned to
each of the participating entities. A Domain Name Service resolves queries for
these names into
IP addresses
for the purpose of locating computer services and devices worldwide. By
providing a worldwide, distributed
keyword-based redirection
service, the Domain Name System is an essential component of the functionality
of the
Internet.
An often-used analogy to explain
the Domain Name System is that it serves as the
phone book for
the Internet by translating human-friendly computer
hostnames into
IP addresses. For example,
the domain name
www.example.com
translates to the addresses 192.0.43.10 (
IPv4) and 2620:0:2d0:200::10
(
IPv6). Unlike a phone
book, DNS can be quickly updated and these updates are distributed, allowing a
service's location on the network to change without affecting the end users,
who continue to use the same hostname. Users take advantage of this when they
recite meaningful
Uniform
Resource Locators (URLs) and
e-mail addresses without
having to know how the computer actually locates the services.
The Domain Name System
distributes the responsibility of assigning domain names and mapping those
names to IP addresses by designating
authoritative
name servers for each domain. Authoritative name servers are
assigned to be responsible for their particular domains, and in turn can assign
other authoritative name servers for their sub-domains. This mechanism has made
the DNS distributed and fault tolerant and has helped avoid the need for a
single central register to be continually consulted and updated. Additionally,
the responsibility for maintaining and updating the master record for the
domains is spread among many
domain name
registrars, who compete for the end-user's, domain-owner's,
business. Domains can be moved from registrar to registrar at any time.
The Domain Name System also
specifies the technical functionality of this database service. It defines the
DNS protocol, a detailed specification of the data structures and communication
exchanges used in DNS, as part of the
Internet
Protocol Suite.
The Internet maintains two
principal
namespaces,
the domain name hierarchy and the
Internet Protocol (IP)
address spaces.
[2]
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 name, such as address (A) records, name server (NS)
records, and mail exchanger (MX) records (see also
list of DNS
record types); a DNS name server responds with answers to queries
against its database.
Research courtesy of Wikipedia
Images courtesy of Wikimedia under The Commons Agreement
http://en.wikipedia.org/wiki/File:Internet_map_1024.jpg
On this Day: 1st January 1985 – The Internet's Domain Name System is created
