Networking II – SS3 Digital Technologies Lesson Note (First Term)

An IP address is the unique address of a device on the internet, like a house address for a letter. Networks can be divided into smaller subnets, and devices follow rules called protocols to understand each other. Data travels as numbered packets, which TCP/IP sends and reassembles in the right order.

Behavioural objectives

By the end of the lesson, students should be able to:

• explain what an IP address is and name its two parts;
• state the difference between IPv4 and IPv6;
• explain subnetting and give reasons for doing it;
• define a protocol and state the use of HTTP/HTTPS, FTP, SMTP and IP;
• describe how TCP and IP move data as packets.

What is an IP address?

Imagine you want to send a physical letter to a friend. If you do not write their house address on the envelope, the postman will not know where to take it.

On the internet, every device (your phone, your laptop, even a smart fridge) has a unique “house address” called an IP Address (Internet Protocol Address). An IPv4 address usually looks like this: 192.168.1.15.

What are the two parts of an IP address?

1. The Network ID: Think of this as the street name. All houses on the same street share this part.
2. The Host ID: Think of this as the house number. This must be unique so the postman knows exactly which door to knock on.

What is the difference between IPv4 and IPv6?

When the internet first started, IPv4 was used. These addresses are made of 4 sets of numbers. There are billions of people on earth, and most of us have 3 or 4 devices, so IPv4 addresses have run out. To fix this, IPv6 was created.

What is subnetting?

Imagine you have a giant hall with 200 students. If everyone talks at once, it is chaos (this is called “Network Congestion”). To fix this, you put up glass walls to divide the big hall into 4 smaller classrooms. Now, each group can focus without hearing the others.

Subnetting works in the same way. It is the process of splitting one large network into smaller, manageable sub-networks (subnets).

Why do we use subnetting?

• Security: Students in Classroom A cannot see what is on the board in Classroom B.
• Speed: It reduces “traffic jams” on the network.
• Organisation: It is easier for a network administrator to find where a problem is.

What are protocols?

A protocol is just a fancy word for a “rule”. For two people to communicate, they must speak the same language. If I speak Yoruba and you speak French, we have no protocol, and communication fails.

These are the common “languages” of the internet:

• HTTP/HTTPS: The language for web browsers. HTTPS is the “secure” version, so always look for the padlock.
• FTP (File Transfer Protocol): The rule used when you are uploading or downloading large files.
• SMTP: The rule for sending emails.
• IP (Internet Protocol): The rule that handles the actual “addressing” and moving of data packets.

How does a packet travel (TCP/IP)?

When you send a photo on WhatsApp, it does not travel as one big chunk. It is chopped up into tiny pieces called packets.

Think of a Lego castle. You cannot mail the whole castle in one box, so you break it into individual bricks, put them in envelopes, and mail them.

What are the steps in the TCP/IP process?

1. TCP (the manager): Chops the data into packets and numbers them (1, 2, 3…).
2. IP (the delivery driver): Delivers the packets to the right address.
3. TCP (the manager) at the other end: Receives the packets, checks if any are missing, and puts them back together in the right order.

Key points

• IP address: Your unique ID on the internet.
• IPv6: The newer address type, with more space.
• Subnetting: Cutting a big network into smaller, faster pieces.
• Protocols: The set of rules that allow devices to understand each other.

Evaluation

1. What is an IP address? Name its two parts.
2. State two differences between IPv4 and IPv6.
3. What is subnetting? Give two reasons for doing it.
4. What does HTTPS stand for in simple terms, and what should you look for in your browser?
5. Describe what TCP and IP each do when you send a photo on WhatsApp.

Assignment

1. Use an analogy of your own, such as a street, a school or a market, to explain the Network ID and the Host ID.
2. List the four protocols in this lesson and write one sentence on the use of each.