Introduction to Networking – JSS2 Computer Hardware & GSM Repair Lesson Note (Second Term)

A computer network is two or more computers connected together so that they can share data, devices and services.

Behavioural objectives

1. Define a computer network and give three reasons for using one.
2. Describe a LAN and a WLAN and state one feature of each.
3. Explain what the Internet is and define the Web, ISP and the cloud.
4. State the job of a NIC, a router, a modem and a switch.
5. Compare a LAN with the Internet using size, connection, ownership and example.

What is a computer network?

A computer network is a group of computers and other devices linked by cable or by radio waves to share information.

• Everyday meaning: a network of people is a group who talk and share information, such as friends or family.
• Computer meaning: devices in a network send files and messages to each other instantly.
• Without a network: you copy a file onto a USB drive and carry it to your friend.
• With a network: you send the file through a cable or through the air.
• Node: any device on a network, such as a computer, phone or printer.

Why do we use computer networks?

We use networks to share files, share hardware and communicate.

1. Sharing files: sending photos, music or homework.
2. Sharing hardware: five computers can all use the same one printer.
3. Communication: sending emails or chatting.
4. Sharing an internet connection: many devices can use one connection.

What is a LAN?

A LAN (Local Area Network) is a network that covers a small area, such as a school computer lab, a home or one office building.

• Connection: most LANs use Ethernet cables to join computers to a central box called a switch or a router.
• Speed: computers are close together, so a LAN is usually very fast.
• Example: all computers in a school lab connected to one printer.

What is a WLAN?

A WLAN (Wireless Local Area Network) is a LAN that uses radio waves instead of cables, and you know it as Wi-Fi.

• How it works: computers and phones use radio waves to talk to a wireless access point, the box with blinking lights and antennas.
• Benefit: you can move around with a laptop or phone and stay connected while close to the signal.
• Constraint: the further you move from the router, the weaker the signal becomes.

How does a wired LAN differ from a WLAN?

What is the Internet?

The Internet is a global network that connects millions of smaller networks (LANs) across every country.

• Nickname: the “network of networks”.
• Comparison: a LAN is like a conversation between friends in a room, while the Internet is like a conversation between people all over the world.

What are the basic Internet terms?

The basic Internet terms are the Web, ISP and the cloud.

1. The Web (WWW): the collection of websites you see when you use a browser such as Chrome or Safari.
2. Browser: a program used to open and read websites.
3. ISP (Internet Service Provider): a company, such as MTN, Airtel or Glo, that you pay for access to the Internet.
4. The cloud: online storage where your files are kept on another company’s computers, as in Google Drive or iCloud.

What hardware is used in a network?

Network hardware is the set of devices that join computers together and let them exchange data.

• NIC (Network Interface Card): the “plug” inside a computer that lets it join a network.
• Ethernet cable: the cable with a plastic clip that carries data between a computer and a switch or router.
• Switch: the central box that joins the computers in a LAN.
• Router: the “traffic police” that sends data to the right computer, so your message does not appear on your neighbour’s screen.
• Modem: the “translator” that changes signals from your ISP into data your computer understands.
• Wireless access point: the device that gives Wi-Fi to phones and laptops.

What is the difference between a LAN and the Internet?

A LAN is a small private network in one place, while the Internet is the worldwide network of networks that no single owner controls.

Teacher’s note

• Show: an Ethernet cable, the one with the clear plastic clip.
• Point out: the router in the school office or lab.
• Compare: let students see the difference between a wired and a wireless connection.

Evaluation

1. If all the computers in the school lab are connected to one printer, what type of network is that?
2. What is the full meaning of WLAN?
3. What is the job of an ISP?
4. Name one advantage of a WLAN over a wired LAN.
5. State the job of a router and of a modem.

Assignment

In your notebook, list four devices used in a school computer lab network and state the job of each. Then say whether your school lab uses a wired LAN, a WLAN or both.