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WHAT IS Domain Name System

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					                             WHAT IS Domain Name System

A domain name is an identification string that defines a realm of administrative autonomy,
authority, or control in the Internet. Domain names are formed by the rules and procedures of
the Domain Name System (DNS).

Domain names are used in various networking contexts and application-specific naming and
addressing purposes. In general, a domain name represents an Internet Protocol (IP)
resource, such as a personal computer used to access the Internet, a server computer
hosting a web site, or the web site itself or any other service communicated via the Internet.

Domain names are organized in subordinate levels (subdomains) of the DNS root domain,
which is nameless. The first-level set of domain names are the top-level domains (TLDs),
including the generic top-level domains (gTLDs), such as the prominent domains com, net
and org, and the country code top-level domains (ccTLDs). Below these top-level domains in
the DNS hierarchy are the second-level and third-level domain names that are typically open
for reservation by end-users that wish to connect local area networks to the Internet, create
other publicly accessible Internet resources or run web sites. The registration of these domain
names is usually administered by domain name registrars who sell their services to the public.

                                        WHAT IS TLD

A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain
Name System of the Internet.[1] The top-level domain names are installed in the root zone of
the name space. For all domains in lower levels, it is the last part of the domain name, that is,
the last label of a fully qualified domain name. For example, in the domain name
www.example.com, the top-level domain is .com (or .COM, as domain names are not case-
sensitive). Management of most top-level domains is delegated to responsible organizations
by the Internet Corporation for Assigned Names and Numbers (ICANN), which operates the
Internet Assigned Numbers Authority (IANA) and is in charge of maintaining the DNS root
zone.

Originally, the top-level domain space was organized into three main groups, Countries,
Categories, and Multiorganizations. An additional temporary group consisted only of the initial
DNS domain, arpa, intended for transitional purposes toward the stabilization of the domain
name system.

Countries are designated in the Domain Name System by their two-letter ISO country code;
there are exceptions, however (e.g., .uk). This group of domains is therefore commonly
known as country-code top-level domains (ccTLD). Since 2009, countries with non-Latin
based alphabets or scripting systems may apply for internationalized country code top-level
domain names, which are displayed in end-user applications in their language-native script or
alphabet, but use a Punycode-translated ASCII domain name in the Domain Name System.

The Categories group has become known as the generic top-level domains. Initially this group
consisted of GOV, EDU, COM, MIL, ORG, and NET.
In the growth of the Internet, it became desirable to create additional generic top-level
domains. Some of the initial domains' purposes were also generalized, modified, or assigned
for maintenance to special organizations affiliated with the intended purpose.

As a result, IANA today distinguishes the following groups of top-level domains:

   country-code top-level domains (ccTLD): Two letter domains established for countries or
    territories. With some historical exceptions, the code for any territory is the same as its
    two-letter ISO 3166 code.
   internationalized country code top-level domains (IDN ccTLD).
   generic top-level domains (gTLD): Top-level domains with three or more characters
    o unsponsored top-level domains: domains that operate directly under policies
        established by ICANN processes for the global Internet community.
    o sponsored top-level domains (sTLD): These domains are proposed and sponsored by
        private agencies or organizations that establish and enforce rules restricting the
        eligibility to use the TLD. Use is based on community theme concepts.
   infrastructure top-level domain: This group consists of one domain, the Address and
    Routing Parameter Area (ARPA). It is managed by IANA on behalf of the Internet
    Engineering Task Force for various purposes specified in the Request for Comments
    publications.

				
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