Basically, an IP (Internet Protocol) uses a 32 bit IP address which is in IPv4 band so that it can identify the machines on the network. Since the non-technical people can't remember this name with these addresses, these addresses are mentioned in the hierarchical manner. Also, on the internet there are number of machines which are too large in number which in turn is very difficult to remember the addresses of each system on the network. Confusion Between Free and Paid Hosting So, people prefer to remember the names which basically consists the sequence of the numbers or the characters which are chosen from the finite alphabets which has a symbolic meaning of the commercial objects like .com for the commercial or even .edu for the educational institutions. Hence we immediately need a system which will basically convert these names into the IP address and vice versa.
When Internet was a very small network, this would have been possible in keeping the IP address to the name mapping into the table which s basically stored in the HOST file. So, when HOST wants the IP address for the given name, the name matched in the table and then the corresponding IP address is used for the communication. The set of machine names are used throughout the internet is called as the Flat Namespace. But, since the Internet today is very vast, mapping cannot be stored on a single machine and also it's difficult to access the same machine from all computers on the internet which is a global network as the amount of traffic generated in the local net where the mapping is stored is un imaginable and is very huge. Also, it is very impossible to update all the host files present all across the World every time whenever there is any change. So, the solution to this problem is that you need to divide the huge amount of information about the mapping of all the machines on the Internet into the smaller parts and store the same as the host file on different machines all over the globe.