Domain names are the alternate address names for IP address, Domain names(eg. example.com) are the easiest way to remember the web address instead on remember IP address(eg. 255.168.48.9). And these domain names are pointing to IP address. Domain Name System(DNS) matches the domain name to IP address.
Every device in the public internet have IP address which is in numeric format(eg. 255.168.48.9), and this string of numeric numbers are difficult to remember, so we assign Domain names for this IP address.
A Domain name(DN) can be used as a website, email accounts
A domain consist of a minimum a Top Level Domain(TLD) and a Second-Level Domain(SLD)
http://example.com/
“.com” is the Top Level Domain
“example” is the Second level domain(SLD) of .com
Structure of Domain Name
Domain name structure can be separated by periods
the right side of the domain is called extensions which are called as TLDs
and left to that called as Second Level Domain(SLD).
SLD.TLD
SubDoamin.SLD.TLD
Sub Domain
A Sub Domain is the subdivision of domain name and you can place unique content for each sub domain or use for unique purpose for each sub domain
en.example.com for English version
ch.example.com for Chinese version
http://www.example.com/
“www” is the sub domain of example.com
another example is
http://blog.example.com/
“blog” is the sub domain of example.com
A domain can have multiple subdomains, it all depends on your hosting providers, some allow to create unlimited number of subdomains for free and some limit the number.
Top Level Domain (TLD)
Top Level Domains are also called as extensions which are the last part of the domain name (suffix of a domain) or the right side of the domain name eg.: .com, .net, .info
There are different types of TLDs
gTLD, ccTLD, geoTLD
Generic Top Level Domain(gTLD)
gTLDs are one of the category in TLDs
some gTLDs are available to register for any one and someor sponsored TLDs which can be registered by only who engaged with that industry
.com, .net, .org .info – anyone can register these domains
.biz, .name, .pro anyone can register these domains but use for their specified purpose
sponsored domains are .aero, .asia, .cat, .coop, .edu, .gov, .int, .jobs, .mil, .mobi, .tel, .travel, .xxx
.gov used by government agencies in USA
.edu used by educational institutions in USA
new gTLD
ICANN hopes to expand domain name availability.
some of them are
.xyz, .club, .wiki, .car, .site, .website
there are currently 1000+ new gTLD are available to register and much more are coming
Country Code Top Level Domains (ccTLD)
Country Code Top Level Domains(ccTLD) composed of two characters
ccTLD represents county names and territories
some of them are
.us which represent USA
.in which represent India(Bharat)
.jp for Japan
.cn for China
.de for Germany
There are 252 ccTLDs, which represents countries and territories around the world.
geoTLD
Geo Top Level Domain represents geographic, geopolitical, ethnic, social or culture
eg. “.asia ” represents Asia continent
“.eu” represents Europe continent
Brand TLD
Corporations can use their brand name as the Top Level Domain.
eg. .aws, .google, .apple, .bing
some companies use their company name as TLD and product name as SLD
Internationalized Domain Name(IDN)
IDN supports to register Domain Name in multiple Languages, i.e which include non-ASCII Characters
IDN are in different languages such as Arabic, Chinese, Hindi, Russian, Tamil, Thai, Japanese and more
Each Language can have multiple TLDs and ccTLDs.
A .com domain is there in many Languages.
.com of Hindi is there “.कॉम”
Second Level Domain(SLD)
Second Level Domain will comes to the left side of the TLDs
from the right side the first part is the Top Level Domain (eg. .com, .net ) and then Second level Domain
example.com
“example” is the Second Level Domain
A Second Level Domain can be any letters(A-Z), Numbers(0-9), Hyphens(“-“), but hyphens should not be the first or last character of the domain.
A Domain name can be a total of 63 letters, excluding extensions
Note: IDN comes in different languages Chinese, Hindi and in many more languages
Country code Second Level Domain(ccSLD)
ccSLD it the second level domain for extension of country codes TLDs (ccTLD)
example.us
.us is the ccTLD and example is the SLD for a ccTLD so called as ccSLD
Restriction on Domain Registration :
For the majority of domain extensions there is no restrictions, but Some Domain Extensions are reserved for special purpose.
Some Restricted domain need Local physical address,
and some Sponsored domain are restricted based on the category, who engaged within the specific industry can only register.
eg. .jobs can register who involved in Human Resources