A
domain name is a component of a
Uniform Resource Locator (URL) used to access
web sites.
For Example
URL:
http://www.almarit.com/index.htm
Top-level domain name:
.com
Second-level domain name:
almarit.com
Host name:
www.almarit.com
A
domain name may point to multiple
IP addresses to provide server redundancy for the services delivered. This is used for large, popular
web sites. More commonly, however, one server at a given
IP address may also
host multiple
web sites in different
domains. Such address overloading enables
virtual web hosting commonly used by large
web hosting services to conserve
IP address space. It is possible through a feature in the
HTTP version 1.1 protocol, but not in
HTTP 1.0, which requires that a request identifies the
domain name being referenced
Below the
top-level domains in the
domain name hierarchy are the
second-level domain (SLD) names. These are the names directly to the left of
.com,
.net, and the other
top-level domains. As an example, in the domain
demo.almarit.com,
almarit is the
second-level domain. The hierarchical
DNS labels or components of
domain names are separated in a fully qualified name by the full stop (
dot,
. ).
Every
domain name has a suffix that indicates which
top level domain (TLD) it belongs to. There are only a limited number of such domains.
For example:
gov - Government agencies
edu - Educational institutions
org - Organizations (nonprofit)
mil - Military
com - commercial business
net - Network organizations
ca - Canada
th - Thailand
The Internet is based on
IP addresses, not
domain names, every
Web server requires a
Domain Name System (
DNS) server to translate
domain names into
IP addresses.
The
Internet Corporation for Assigned Names and Numbers (
ICANN) has overall responsibility for managing the
DNS. It administers the
root domain, delegating control over each
TLD to a
domain name registry. For
ccTLDs, the domain registry is typically installed by the government of that country.
ICANN has a consultation role in these domain registries but cannot regulate the terms and conditions of how
domain names are delegated in each of the
country-level domain registries. On the other hand, the
generic top-level domains (
gTLDs) are governed directly under
ICANN, which means all terms and conditions are defined by
ICANN with the cooperation of each
gTLD registry
A few companies have offered low-cost, below-cost or even cost-free
domain registrations with a variety of models adopted to recoup the costs to the provider. These usually require that
domains be hosted on their
website within a framework or portal that includes advertising wrapped around the
domain holder's content, revenue from which allows the provider to recoup the costs.
Domain registrations were free of charge when the
DNS was new. A
domain holder (often referred to as a
domain owner) can give away or sell infinite number of subdomains under their
domain name. For example, the owner of example.edu could provide subdomains such as foo.example.edu and foo.bar.example.edu to interested parties.
