What is DNS?

The domain name system (DNS) is the way that Internet domain names are located and translated into IP addresses - it is nothing more than a directory distributed throughout the Internet.

If DNS were to fail, you would not be able to find any websites which are hosted on a different network and emails would be undeliverable
How does DNS work?

Every time you enter a domain name you use the Internet's DNS Servers to translate the domain name into the IP address to find the web page.
DNS Servers constantly accept requests to do this:

• from programs to convert domain names into IP addresses
• from other name servers to convert domain names into IP addresses

A DNS Server does one of four things with a request:

• It can answer the request if it knows the IP address for the domain.
• It can contact other name servers to find the IP address for the name requested.
• It can say, "I don't know the IP address for the domain you requested, so try this IP address of a name server that may."
• It can return an error message for a non existent or invalid domain name.

If the DNS says YES it can answer request

It may already know the IP address for ‘www.text.co.uk’. If the same request has come in recently it may have cached the IP address so it returns the IP address immediately, i.e. the server then gives the location of the site on the server.

If the DNS says NO it cannot answer request

It starts contacting one of the root name servers. (The root servers know the IP address for all of the name servers that handle the TLDs.)

Every name server has a list of all root servers. It contacts the first root server in the list, and if that doesn't work it contacts the next one in the list, and so on until it finds the IP address.

The IP address is returned and the web page for www.text.co.uk displayed – Result!

Click here to find out more about DNS