[ Thanks to Andrew
Weber for this link. ]
“Originally, users of the Internet, when it was still
known as ARPAnet, were forced to use a hosts file called HOSTS.TXT
which did the conversion of the IP Address (like 192.168.2.34) to a
host (like mail.example.org) by downloading a large file from a
central location that listed all of the hosts on the Internet and
their IP Addresses. As the network grew, this soon became a
situation that could not continue based on the sheer size and the
rapid growth of the Internet. Domain Name Service (DNS) was created
in 1983 out of the necessity to convert IP Addresses like
192.168.9.2 to domain names like example.com. DNS is a distributed
database, what this means is that no one computer is used to
maintain a complete database of all of the domains on the Internet.
Instead this information is distributed across many computers. To
further understand how this works, take a look at the DNS
structure:“Notice how the DNS namespace resembles an inverted tree. The
top node, symbolized by a single dot, is known as the root. Below
the root, you have the top-level domains like: com, net, org, mil,
gov, etc. There are many top-level domains and now even
international domains so the number is almost unlimited for
top-level domains.”