Computer Network Class 4 Computer Notes and Questions

Please refer to Computer Network Class 4 Computer notes and questions with solutions below. These revision notes and important examination questions have been prepared based on the latest Computer books for Class 4. You can go through the questions and solutions below which will help you to get better marks in your examinations.

Class 4 Computer Computer Network Notes and Questions

Computer network

• A computer network is a set of computers connected together for the purpose of sharing resources.
• The most common resource shared today is connection to the Internet. Other shared  resources can include a printer or a file server.
• It is possible to connect a number of computers and other electronic devices to create a computer network.
• The computers and devices which are part of the network can “talk” to each other and exchange information. Firewalls are commonly used to protect the network.
• In general, networks that use cables to connect can operate at higher speeds than those using wireless technology.
• In addition to the computers and devices which are connected, other devices are often needed for the network to work correctly.
• Examples for such devices include hubs and switches. Different kinds of network can be connected to each other with a router.

Evolution of Network
The concept of Internet was originated in 1969 and has undergone several technological and infrastructural changes as discussed below.

• The origin of Internet was devised from the concept of Advanced Research Project Agency Network (ARPANET).
• ARPANET was developed by United States Department of Defense.
• Basic purpose of ARPANET was to provide communication among the various bodies of government.
• Initially, there were only four nodes, formally called Hosts.
• In 1972, the ARPANET was spread over the globe with

Classification of network
Generally, networks are distinguished based on their geographical span. A network can be as small as distance between your mobile phone and its bluetooth headphone and as large as the internet itself, covering the whole geographical world.

Personal Area Network

• A Personal Area Network (PAN) is the smallest network which is very personal to a user. This may include bluetooth enabled devices or infra-red enabled devices.
• PAN has connectivity range up to 10 meters. PAN may include wireless computer keyboard and mouse, Bluetooth enabled headphones, wireless printers and TV remotes.

• For example, Pico-net is Bluetooth-enabled Personal Area Network which may contain up to 8 devices connected together in a master-slave fashion

Local Area Network

• A computer network spanned inside a building and operated under single administrative system is generally termed as Local Area Network (LAN). Usually, LAN covers an organizations’ offices, schools, colleges or universities. Number of systems connected in LAN may vary from as least as two to as much as 16 million.
• LAN provides a useful way of sharing the resources between end users.
• The resources such as printers, file servers, scanners, and internet are easily sharable among computers.

• LANs are composed of inexpensive networking and routing equipment. It may contain local servers serving file storage and other locally shared applications. It mostly operates on private IP addresses and does not involve heavy routing. LAN works under its own local domain and controlled centrally.
• LAN uses either Ethernet or Token-ring technology. Ethernet most widely employes LAN technology and uses star topology, while Token-ring is rarely seen.
• LAN can be wired, wireless, or in both forms at once.

Metropolitan Area Network

• The Metropolitan Area Network (MAN) generally expands throughout a city such as cable TV network. It can be in the form of Ethernet, Token-ring, ATM, or Fiber Distributed Data Interface (FDDI).
• Metro Ethernet is a service which is provided by ISPs. This service enables its users to expand their Local Area Networks. For example, MAN can help an organization to connect all of its offices in a city.

• Backbone of MAN is high-capacity and high-speed fiber optics. MAN works in between Local Area Network and Wide Area Network. MAN provides uplink for LANs to WANs or internet.

Wide Area Network

• As the name suggests, the Wide Area Network (WAN) covers a wide area which may span across provinces and even a whole country.
• Generally, telecommunication networks are Wide Area Network. These networks provide connectivity to MANs and LANs. Since they are equipped with very high speed backbone, WANs use very expensive network equipment.

• WAN may use advanced technologies such as Asynchronous Transfer Mode (ATM), Frame Relay, and Synchronous Optical Network (SONET). WAN may be managed by multiple administrations. 

Advantages of Networking

• A network of networks is called an internetwork, or simply the internet. It is the largest network in existence on this planet.
• The internet hugely connects all WANs and it can have connection to LANs and Home networks. Internet uses TCP/IP protocol suite and uses IP as its addressing protocol.
• Present day Internet is widely implemented using IPv4. Because of shortage of address spaces, it is gradually migrating from IPv4 to IPv6.
• Internet enables its users to share and access enormous amount of information worldwide. It uses WWW, FTP, email services, audio and video streaming, etc. At huge level, internet works on Client-Server model.
• Internet uses very high speed backbone of fiber optics. To interconnect various continents, fibers are laid under sea known to us as submarine communication cable.
• Internet is widely deployed on World Wide Web services using HTML linked pages and is accessible to clients as Web Browsers.
  When a user requests a page using some web browser located on some Web Server anywhere in the world, the Web Server responds with the proper HTML page.

Internet is serving many purpose and is involved in many aspects of life. Some of them are:

• Web sites
• E-mail
• Instant Messaging
• Blogging
• Social Media
• Marketing
• Networking
• Resource Sharing
• Audio and Video Streaming

Basic requirements for an internet Connection
The various requirements for connecting to an internet are:

• A Computer: A processing device like PC, laptop, smartphone or a tablet is required to access the internet facilities.
• Modem: Modem stands for Modulator Demodulator. It is a device which connects one computer to another with the help of telephone lines. It is through modem that a computer sends and receives all the data. A modem can be fitted into the computer (internal modem) or attached from outside (External modem).
  A modem is a small box shaped device which may or may not be connected to a telephone line. The modem is provided to the user by Internet Service Provider.

• Internet Connection: Internet connection is provided by the Internet Service Providers (ISPs). Many companies provide internet connections. For example: Reliance  Communications, Airtel, MTNL, BSNL, etc. 

Basic Networking Devices

• Network Hub: Network Hub is a networking device which is used to connect multiple network hosts. A network hub is also used to transfer data.
• Network Switch: Like a hub, a switch also works at the layer of LAN (Local Area Network).
• Modem: It is a device that is used to connect with internet. Technically it is a device which enables digital data transmission to be transmitted over the telecommunication lines.
• Network Router: A router is a network device which is responsible for routing traffic from one to another network. These two networks could be a private company network to a public network. 

OSI (Open Systems Interconnection) model:
OSI is a reference model for how applications communicate over a network. A reference model is a conceptual framework for understanding relationships. The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs can interoperate and facilitate a clear framework that describes the functions of a networking or telecommunication system.
OSI Modal contains seven layers. These are:

Protocol 
A protocol is a set of rules and guidelines for communicating data. Rules are defined for each step and process during communication between two or more computers. Networks have to follow these rules to successfully transmit data.

There are different types of Protocol such as:

• Internet Protocol (IP)
• Transmission control Protocol (TCP)
• File Transfer Protocol (FTP)
• Hyper Text Transfer Protocol (HTTP)
• Network News Transfer Protocol(NNTP)
• Internet Address Protocol
• Ethernet

Internet Protocol (IP): The Internet Protocol (IP) is the principal communication protocol in the Internet protocol suite for relaying data grams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

Transmission control Protocol (TCP): TCP (Transmission Control Protocol) is a standard that defines how to establish and maintain a network conversation via which application programs can exchange data. TCP works with the Internet Protocol (IP), which defines how computers send packets of data to each other.

File Transfer Protocol (FTP): FTP is an acronym that stands for File Transfer Protocol. A FTP client is a program that allows you to easily move files from one computer to another.

Hyper Text Transfer Protocol (HTTP): HTTP (Hypertext Transfer Protocol) provides a network protocol standard that web browsers and servers use to communicate. It is easy to recognize this when visiting a website because its written right in the URL (http://www.abc.com).

Network News Transfer Protocol(NNTP): NNTP (Network News Transfer Protocol) is the protocol used to connect to net servers and transfer news group articles between systems over the Internet. It is designed specifically for news group articles.