Domain Name Service (DNS) is a web service which converts a particular type name to an ip address. A simple example, you type the name of a web domain in your browser. Your browser contacts a DNS which replies with the ip address where the web domain is hosted. DNS also provides conversions of names for sub-domains, mail servers and other types of web services. DNS is also can use a 'round robin' concept to distribute visitors between different redundant mirrored web servers can also have geographical advantages.