Category: Administrative Domain Based Classification

Describes the different networks under the administrative domain based classification

What are Public and Private networks?

Explains the concept of Public and Private networks

  • A public network is one that is accessible via. the Internet. That means that computers/nodes of a public network are reachable from any computer that has connectivity to the Internet.
  • Computers on a public network would use the TCP/IP suite of protocols for communication.
  • A private network is one that is hidden from the public Internet and hence computers/nodes of a private network are inaccessible to computers that are not part of the private network. Examples are: Enterprise networks, defence networks etc.
  • Computers inside a private network need not necessarily use only the TCP/IP set of protocols. They can have their own set of protocols, as long as all the nodes of the private network can understand the same.

What is Internet?

Explains the meaning of the term “Internet” along with an example Internet topology

  • As the name indicates, Internet is a connection of multiple networks or a network of networks.
  • Internet is the name given to the set of all public data networks put together. Due to this definition, it can be considered as the mother of all networks and is the largest network. Also, it is not owned by a single administrative domain.
  • Another way of looking at Internet is that it can be considered as the collection of all computers on the earth that is connected to the public data network.
  • All communicating computers/nodes on the Internet use the TCP/IP suite of protocols for communication. 
  • Each computer/communicating end node requires a public IP address for it to be reached from other public computers on the Internet.

The diagram given below illustrates a portion of the internet:

A Typical portion of Internet

  • As seen from the diagram, all types of networks (e.g. home networks, enterprise networks, campus networks etc.) connect to the Internet.
  • Each network connects to the Internet through different ISPs and through different media (wired/wireless).
  • The beauty of the Internet is that though it is not under the control of a single administrative domain/ISP, computers connected to it can still communicate between them and exchange meaningful information, irrespective of their geographical location, thereby making the Internet an information power house.