Though IP addresses allow computers and routers to identify each other efficiently, humans prefer to work with names rather than numbers. The Domain Name System - DNS - supports this process.

DNS allows nodes on the public Internet to be assigned both an IP address and a corresponding name, called a domain name.

For DNS to work as designed, these names must be unique worldwide.

DNS Name Space
DNS is a hierarchical system. DNS organizes all registered names in a tree structure.
At the base or root of the tree are a group of top-level domains including familiar names like com, org, and edu and numerous country-level domains like lk (Sri Lanka) .

Below this level are the second-level registered domains such as kauta.com. These are domains that organizations can purchase from any accredited registrars.

For nodes in the com, org, and edu domains, the Internet Corporation for Assigned Names and Numbers (ICANN) oversees registrations.

DNS Root Level and Other Servers
DNS is also a distributed system. The DNS database contains a list of registered domain names. It further contains a mapping or conversion between each name and one or more IP addresses.

no one computer holds the entire DNS database. Each DNS server maintain just one piece of the overall hierarchy - one level of the tree and then only a subset or zone within that level.

The top level of the DNS hierarchy, also called the root level, is maintained by a set of 13 servers called root name servers.

DNS Resolvers
DNS works in a client/server fashion. DNS servers respond to requests from DNS clients called resolvers. ISPs and other organizations set up local DNS resolvers as well as servers.

DNS and DHCP
DNS was not designed to work with dynamic addressing such as that supported by DHCP. DNS requires that fixed (static) addresses be maintained in the database. Web servers in particular require fixed IP addresses for this reason.