DNS, or Domain Name System, is a network service which translates host and domain names into IP addresses, or IP addresses into host and domain names. It is designed as a worldwide, distributed hierarchical database.

Central to the basic concepts of DNS are the concepts of the Root, domains, fully qualified domain names (FQDN), delegation, and forwarding.

A Domain is a named container. Each domain is separated by a dot "." Certain domains are called Top Level Domains, which are the main containers' used on the internet for domains to fall under. Some examples of Top Level Domains include com, edu, net, org, and arpa. There are a total of 20 generic TLD's, the special root and arpa TLD's, as well as a number of two-lettered TLD's representing international country names (for example, UK, US, and UY for the United Kingdom, United States of America, and Uruguay respectively).

Each domain is registered via ICANN (or one of its authorized registrars) and each registered domain has associated with it a pair of DNS servers IP addresses. These servers are considered authoritative for information contained within that sub domain, and queries from the Root will be refered to these servers by other DNS servers asking for information. A domain or a part of a domain can then be futher delegated to another server or set of servers. One server can be authoritative for more then one domains, or more then one server can be authoritative for one domain.

Each Top Level Domain is listed via the Root. Each TLD server conatins within the information about the domains which fall under the TLD. For example, the TLD server for the TLD COM has the information for the DNS servers authoritative for IBM (dot com), HP (dot com), United (dot com), etc.

A fully qualified domain name consists of a host name followed by a dot ( . ) followed by any number of sub domains and a dot, followed by a top-level domain. All Top Level Domains are properly terminated by a final dot ( . ) which represents the Root (though traditionally the last dot is left off in common use, it's inclusion is very important when configuring BIND, a widely used DNS application and server).

The worldwide DNS system is comprised of a number of parts which comprise the whole. It starts with the Root. The Root, otherwise known as " . " is the origin of all domain names. The Root is currently maintained by the Internet Assigned Numbers Authority group, a part of ICANN (Internet Corporation

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