Domain Name Servers (DNS) are the equivalent of a phone book for the internet.
They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses.
Domain names might be easy for people to understand but not quite so for computers. Computers and machines are able to access websites based on IP addresses.
All information in regards to Domain Name Servers are kept in the Central Registry. Internet Service Providers (ISP), Host Companies get updated DNS information from the Central Registry.
Example, typing in this web address geeksvillage.com, your ISP will view the DNS that is linked with the domain name and translate it into an IP address that a machine can understand.
it usually takes about 12-48 hours for the domain name servers world-wide to be updated and able to access the information. This 48-hour period is referred to as propagation.