Domain Name System or DNS

According to mathematics a domain is the set of values in wich a function is defined.In practical use a domain is the range in which one can exist.But a domain in the internet is the name of the website.

For example in http://www.google.com "google" is the name of the domain.All the domains that end with a .com are generally referred to as "dot-com" domains. There are several types of domains like .org(for organizations), .net(for network related) , .us,.sg,.ge,.in(location specific) domains while .com are commercial domains. However it is not compulsary that an organization should have a .org domain and similarly for the other types of domains also. But what happens after you type in the domain name in your browser window?

Resolving Host
You often see this message in the browser while the browser is searching for the website. Soon you see the website in the browser. This webpage might be coming from another continent too. These webpages are stored in webservers which can be physically located in any part of the network-Internet. Each webserver has a specific and unique IP address which is used for identifying it in the netrwork. As soon as you type in the domain name, the Domain Name System or DNS translates it into IP address. For example www.google.com translates to 74.125.19.99. You can directly type in this IP address of any domain to get the website. However, domain names are meaningful and easy to remember and that is what they are meant for.

This can be compared to the phone book in mobile phone. You type the name of your friend and hit the call button, your mobile phone dials the number of your friend and the network connects it. Here DNS(Domain Name System) is the mobile phone and the contact book need not be maintained by us and websites are still our friends.

As soon as the webserver or the host gets a request of webpage it sends the webpage to the client. Hence, a unique domain name will always be directed to the same servers and the job of the provider is to serve the requests of all the clients.