Essential Concepts - Computer Network and Network Host

Now, let us begin to understand some of the basic concepts that are essential in laying the groundwork for our journey of learning how to hack. Before actually jumping into the hands-on approach, it is highly necessary for one to have a thorough understanding of the basics of computer network and their working model. In this chapter you will find a brief description of various concepts and terminologies related to computer networks, encryption and security.

COMPUTER NETWORK

A computer network is a group of two or more computers linked together so that communication between individual computers is made possible. Some of the common types of computer network include:

• Local Area Network (LAN) : This is a type of computer network where interconnected computers are situated very close to each other say for example, inside the same building.
• Wide Area Network (WAN) : This is a type of computer network where interconnected computers are separated by a large distance (a few km to few hundreds of km) and are connected using telephone lines or radio waves.
• Internet : The Internet is the largest network which interconnects various LANs and WANs. It is a global system of various interconnected computer networks belonging to government or private organizations.

NETWORK HOST :

A network host (or simply referred to as a host) can be any computer or network device connected to the computer network. This computer can be a terminal or a web server offering services to its clients. When a number of computers are connected with the help of any type of the networks mentioned above, the computer which provides different types of services to other computer is called a Network Host.

Here, it could be identified as a server-client relationship. The one which provides services to other is called as a Server and the one which takes the service is called a Client.

Taking some common examples to understand the phenomenon :

1. Take the example of world's best search engine, Google. When you search something in google, what happens? What do you think! In reality, Google is a large server of computers interconnected using any of above mentioned computer networks and it serves as a Host to us. Data we search, is in fact stored in the computers that are interconnected. The Main computer searches for the data in other computers and returns all the data found, to our computer on the browser.
2. Take a second example for Cloud Storage like Google Drive. You think it as the data is stored online. But did you ever thought where would the data be stored ? In the clouds!!...Here, the data is really stored in a computer which acts as a Host to us and provide the data whenever needed. Here, we are connected to that Host via Internet.