Ans :
The main reason is that each computer network is designed with a specific purpose.
For example, LAN is used to connect computers in a smaller area, and it provides fast
communication. As a result, networks become specialized identify. In many cases,
these networks do not use the same hardware and software technology. It means that,
a computer can communicate with the computers attached to the same network,
because they are indecomposable. As more and more organizations had multiple
computer networks, this became a major issue. As a result, the concept of
internetworking (internet) came into being. This means that there should be a network
of all physically separate networks.
