Chapter 8 Computer network - I class 12th

 Evolution of Networking:

Introduction to Computer Networks:

Networking: Network is an interconnection of two or more Computers that are Connected together to share data and information.

Major components of a Computer Networks are :

(a) Hosts/Nodes (such as PC, laptops, smartphones etc.)
(b) Servers
(c) Clients
(d) Network hardware (such as NIC, router, switch, hub etc.)
(e) Communication channel (such as cables, radio-links etc.)
(f) Software (such as protocols, network operating system etc.)
(g) Network services (such as BNS, File-sharing etc.).

Why do we need network?

1. Fast and Secure Communication

2. Resource sharing

3. Reduce Cost

Benefit of Networking

1) Data Communication and transfer becomes super easy.

2) Communication becomes extremely fast

3) we can share Software / hardware/ storage.

4) Data is Centralized and that's why it is available everywhere.

5) Telecommunication has become extremely fast.

 Types of Networks Based on Geographical Spread

1) PAN (Personal Area Network)
2) LAN (Local Area Network)
3) MAN (Metropolitan Area Network)
4) WAN (Wide Area Network)

Personal Area Network (PAN)- A personal area network (PAN) is the interconnection of information technology devices within the range of an individual person, typically within a range of 10 metres.

LOCAL AREA NETWORK - Small computer networks that are confined to a localised area - upto 1 km - (e.g., an office, a building or a factory) are known as Local Area Networks (LANs).

MAN (Metropolitan Area Network)- MAN (Metropolitan Area Network), which refers to a network that is spread over an area as big as a city, i.e., upto 30-40 km, e.g., cable broadband Internet Services network of a city.

Wide Area Network (WAN)- The networks spread across countries or on a very big geographical area (multiple cities, countries, continents etc.) are known as WANs (Wide Area Networks). A Wide Area Network (WAN) is a group of computers that are separated by large distances and tied together. It can even be a group of LANs that are spread across several locations and connected together to look like one big network.

ARPANET-

ARPANET, or Advanced Research Projects Agency Network, was a computer network that was the precursor to the modern internet.ARPANET was established in 1969 and was operational by 1971. The project was initiated by Bob Taylor,ARPANET was a project of the U.S. Department of Defense that allowed government agencies, research institutions, and private corporations to share information and communicate

NSFNET

NSFNET, or the National Science Foundation Network, was a program that created a network of computer systems to support scientific and engineering research in the United States. The program was funded by the National Science Foundation (NSF) from 1985 to 1995.

The internet

The internet, sometimes simply called the net, is a worldwide system of interconnected computer networks and electronic devices that communicate with each other using an established set of protocols. The internet was conceived by the Advanced Research Projects Agency (ARPA) of the U.S. government in 1969.

Data communication terminologies: 

Data communication: 

Data Communication is Communication of data among multiple devices afficient and accurate. 

components of data communication 

1) sender(source) = This is the device that generate The request/Data/ information

2) Receiver (Destination)= This is the device that accepts The request/Data/ information

3)The message = This is the data or information . A message could be in any form, it may be in form of a text file, an audio file, a video file, etc.

4)communication media =This is the medium through Which request/Data/ information is transferred-

I- Wired 

II- Wireless

5) Protocol = A protocol is "a formal description of message formats and the rules that two or more machines must follow to exchange those messages." 

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