Computer Networks SS1 Digital Technologies Lesson Note

Subject: Digital Technologies 

Class: SS1

What is a Network?

In everyday life, a “network” is just a group of people who stay in touch to share information. A Computer Network is exactly the same thing, but with machines.

Definition: A computer network is a collection of computers and devices connected together so they can share resources (like a printer) and information (like a file or an email).

Why do we bother connecting them?

1. Resource Sharing: Instead of buying 10 printers for 10 offices, you buy one and connect everyone to it.
2. Communication: It allows for instant messaging, emails, and video calls.
3. Data Sharing: It’s easier to send a file over a network than to copy it onto a flash drive and walk it over to another room.

The Three Main Types (LAN, MAN, WAN)

We group networks based on how much “ground” they cover. Think of it like a local street vs. a whole country.

1. LAN (Local Area Network)

This is a network in a small area, like a single room, a house, or a school computer lab. It is very fast and private.

• Example: Your school’s computer lab where all PCs are linked together.

2. MAN (Metropolitan Area Network)

This covers a whole city or a large campus. It’s basically a bunch of LANs joined together.

• Example: A bank that has five different branches across Lagos, all connected to each other.

3. WAN (Wide Area Network)

This covers huge distances—countries or even the whole world! It uses satellites and underwater cables to stay connected.

• Example: The Internet is the biggest WAN in the world.

Network Components (The “Hardware”)

To build a network, you need more than just computers. You need specific “tools” to help the data move.

• The Server: This is the “Big Boss” computer. It’s a powerful machine that provides data or services to the other computers.
• The Client: This is the “Normal” computer (like yours) that requests information from the server.
• Network Interface Card (NIC): A small chip inside your computer that allows it to “talk” to the network.
• Transmission Media: These are the paths data travels on. It can be Wired (Cables) or Wireless (Wi-Fi/Radio waves).

The “Traffic Police” (Hubs, Switches, and Routers)

When many computers are connected, data can get “lost” or “crash” into other data. We use these devices to direct the traffic:

1. Hub: An old device that sends data to everyone on the network, even if it was only meant for one person. It’s not very smart.
2. Switch: A smarter version of a hub. It knows exactly which computer a message is for and sends it only to that machine.
3. Router: This is the most important one for the internet. It connects different networks together. If a message needs to go from your school’s LAN to the Internet’s WAN, the Router is the “Gatekeeper” that shows it the way.

Summary & Network Benefits

To wrap up, networking has changed the world by making information move at the speed of light. Without these connections, we wouldn’t have Google, Social Media, or Online Banking.

Quick Recap Table

Final Thought: Next time you send a WhatsApp message, remember that your phone (the Client) is sending data through a Router via a WAN to reach a Server!

Check for Understanding

1. If you wanted to connect all the schools in your state, would you use a LAN or a MAN?
2. What is the main job of a Server?
3. Why is the Internet considered a WAN?

If your computer has no NIC, can it join a network? Why?