It is a worldwide system which has the following characteristics:

• Internet is a world-wide / global system of interconnected computer networks.

• Internet uses the standard Internet Protocol (TCP/IP)

• Every computer in internet is identified by a unique IP address.

• IP Address is a unique set of numbers (such as which identifies a computer’s location.

• A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name.

• For example, a DNS server will resolve a name to a particular IP address to uniquely identify the computer on which this website is hosted.

• Internet is accessible to every user all over the world.

Evolution of the Internet

The structure and makeup of the Internet has adapted as the needs of its community have changed. Today's Internet serves the largest and most diverse community of network users in the computing world. A brief chronology and summary of significant components are provided in this chapter to set the stage for understanding the challenges of interfacing the Internet and the steps to build scalable internetworks.

Origins of the Internet

The Internet started as an experiment in the late 1960s by the Advanced Research Projects Agency (ARPA, now called DARPA) of the U.S. Department of Defense. DARPA experimented with the connection of computer networks by giving grants to multiple universities and private companies to get them involved in the research.