The Domain Name System (DNS) is a
distributed, hierarchical database whose primary
function is to convert user-friendly
domain names
like www.domain.com into numeric IP addresses
like 10.211.57.180 and vice versa.
The DNS is also used for storing and retrieving
mail-routing information
(MX records)
and various kinds of general administrative information
(for example, host information and
free-format comments).