The DNS Hierarchical Name Space is a map of how DNS

Domain name system

The Domain Name System 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...

 server

Server (computing)

In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

s determine what IP address

IP address

An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...

 to connect to given a URL

Uniform Resource Locator

In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....

Registrars

Registrar

Domain name registrar

A domain name registrar is an organization or commercial entity, accredited by both ICANN and generic top-level domain registry to sell gTLDs and/or by a country code top-level domain registry to sell ccTLDs; to manage the reservation of Internet domain names in accordance with the guidelines of...

s, such as VeriSign

VeriSign

Verisign, Inc. is an American company based in Dulles, Virginia that operates a diverse array of network infrastructure, including two of the Internet's thirteen root nameservers, the authoritative registry for the .com, .net, and .name generic top-level domains and the .cc and .tv country-code...

, the operator of the .com

.com

The domain name com is a generic top-level domain in the Domain Name System of the Internet. Its name is derived from commercial, indicating its original intended purpose for domains registered by commercial organizations...

and .net

.net

The domain name net is a generic top-level domain used in the Domain Name System of the Internet. The name is derived from network, indicating its originally intended purpose for organizations involved in networking technologies, such as Internet service providers and other infrastructure companies...

top-level domain

Top-level domain

A top-level domain is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. 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...

s, let any company, organization, or private individual register a TLD for any number of years. The domain name is then added to the Whois

WHOIS

WHOIS is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block, or an autonomous system, but is also used for a wider range of other information. The protocol stores...

 directory, and may point to a specific DNS server, which translates the domain name into an IP address.

Map

Domain names are read from right to left. Different sub-domains under a domain name are generally used to point to different servers, however, this is not always the case. For example, the wikipedia community might want a Spanish

Spanish language

Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 version of the site to be on a server in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. So, es.wikipedia.org might point to 67.167.39.4, while en.wikipedia.org and database.en.wikipedia.org can both point to 24.73.285.3, just different pages.

.
-----------------------|-----------------------------------
/ / | \ \ \
com net mil org gov int
| | | | | |
google nsf army wikipedia whitehouse fr
/ | \
en es sv
|
database (imaginary)*