Domain Name Service (DNS) was created out of the necessity to convert domain names to IP addresses. DNS is a distributed database, meaning no one computer is used to maintain a complete database of all of the domains on the Internet. This informative Begin Linux report discusses the DNS structure to offer an understanding of how it works.
“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 name to an IP Address (like 192.168.2.34) 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.”