TCP/IP (Transmission Control Protocol/Internet Protocol) was invented by Robert Elliot “Bob” Kahn and Vint Cerf. It is a basic communication protocol which is used to connect the hosts on Internet. It uses the client/server model of communication in which the user requests and it is responded a service by another computer in the network. It is also known as Department of Defense (DoD) model as the development of the networking model was funded by DARPA (An agency of the United States Department of Defense).