JSS 2 First Term

Learning Objectives

• Define a computer network and its purpose.
• Name the types of networks by coverage.
• State the advantages and limitations of networks.
• Compare client-server and peer-to-peer networks.

What is a Computer Network

A computer network is a group of two or more computers connected so that they can share data, programs and resources. Networks make communication faster, reduce the copying of files and allow many people to use the same information at once.

Common reasons for using a network include sharing files and data, sharing hardware such as a printer or scanner, communicating through email and messaging, saving money by sharing one device, and managing all the computers from one place.

Types of Networks

A local area network, or LAN, covers a small area such as one building or campus. It is the most common network in schools and offices, and it is fast because the devices are close together.

A metropolitan area network, or MAN, covers a larger area such as a city. A university with several buildings connected across a city is a MAN.

A wide area network, or WAN, covers a very large area such as a country or the whole world. The internet is the largest WAN. A bank with branches in several cities uses a WAN. A personal area network, or PAN, connects devices around one person, such as a phone and a wireless earpiece.

Advantages of Networks

Networks allow many users to share one printer, one internet connection or one server. Users can open the same files from different computers, and messages can be sent between users at once.

Networks save money because fewer devices are bought, they keep files safely on one server, and they let people work together on the same project from different computers.

Limitations of Networks

Networks have disadvantages. Setting one up can be costly because cables, switches, routers and a server are needed. Connected computers are open to viruses and attackers, and a virus on one computer can spread to all.

Networks also need regular maintenance and skilled staff. If the server fails, many services stop, and if there is no proper backup, data can be lost. Managing a network also requires technical knowledge.

Client-Server and Peer-to-Peer Networks

In a client-server network, one powerful computer called the server provides services and data to the other computers, called clients. The server controls access and stores files centrally. Most schools and businesses use this type because it is easier to manage and more secure.

In a peer-to-peer network, every computer is equal and can act as both a client and a server. There is no central controller. This type is simpler and cheaper but harder to manage and less secure, and it suits small home networks.

Practical Work

1. Draw and label a simple LAN of five computers sharing one printer and one internet connection.
2. List two advantages and two limitations of a computer network from the school lab.
3. Classify these networks as PAN, LAN, MAN or WAN: a home network, a school lab, a city network and the internet.
4. Write two differences between a client-server network and a peer-to-peer network.

Scenario-Based Questions

1. A small school with five computers asks whether it needs a network. Give two reasons why a network is still useful even with so few computers.
2. A company has offices in Abuja, Lagos and Port Harcourt. What type of network connects the offices, and why is it not a LAN?
3. A virus spreads to all the computers in a bank overnight. Which limitation of computer networks does this show?
4. A community library sets up five computers that share one printer and one internet connection. Is this client-server or peer-to-peer? Explain.
5. A small business owner is told that setting up a network will cost a lot. List two advantages that could convince him.
6. A hospital network goes down and no doctor can reach the patient records. Explain one disadvantage of relying on a network and suggest a way to reduce the risk.
7. Explain why the internet is described as the largest WAN in the world.