4. Client-Server & Peer-to-Peer Networks

Networks allow devices to connect and share data, but not all networks work in the same way. The way a network is organised depends on how its devices are expected to communicate and share resources like files, printers, or internet access. Two of the most common models used in the real world are client-server and peer-to-peer.

In a client-server network, one or more central machines—called servers—handle tasks for other devices on the network, called clients. This setup is common in schools, offices, and online services where users need to log in, save work, or access shared systems. The server handles requests from clients and gives access to files, apps, or other resources (devices like printers and scanners) when needed.

On the other hand, a peer-to-peer (P2P) network connects devices without a central authority. Every device, or peer, can directly share things with others. These networks are simpler and cheaper to set up, especially for small spaces like homes or cafés. However, they rely on each peer managing its own data and settings, which can lead to issues with organisation or security.

Many services we use every day—like online document storage or media streaming—are built using the client-server model. These tools, often referred to as cloud services, make it possible to access content from anywhere and work collaboratively, even when people are in different locations.

Learning Objectives

By the end of this lesson, I will be able to:

Describe what a network is and why devices use them.
Explain the difference between client-server and peer-to-peer networks.
Give examples of where each type of network is used in real life.
Identify the benefits and limitations of each model.
Understand how cloud computing works as a client-server system.
Use key terms like server, client, peer, and cloud correctly when talking about networks.

Key Terms

Network – A group of connected devices that share data.

Client – A device that requests services on a network.

Server – A powerful computer that provides services to clients.

Client-Server Network – A network with a central server managing devices.

Peer-to-Peer (P2P) Network – A network where all devices share equally.

Peer – A device in a P2P network acting as both sender and receiver.

Centralised – Controlled by a single server.

Decentralised – No single control; devices manage themselves.

Cloud Computing – Using the internet to access files and apps stored on remote servers.

Data Centre – A building full of servers used for cloud services.

Streaming – Watching or listening to content directly from a server.

Backup – A copy of data stored safely (often in the cloud).

File Sharing – Sending and receiving files between devices.

Access – The ability to open or use files, apps, or services on a network.

Client-Server Networks: One Central Boss

In a client-server network, one or more servers act as the centre of the network. The server is a powerful computer that stores files, manages access, and controls devices like printers. The other computers, called clients, send requests to the server. The server responds with the file, software, or action the client needs.

Everyday Examples:

When you log into any computer at school and your files appear—that’s a client-server network.
Google Drive stores your documents on Google’s servers, not your laptop.
Online games like Fortnite or Roblox use servers to run the game world and connect players.
At school, when you print a file, your computer sends the print job to a central server first.

Why schools and businesses use this model:

Files and settings are stored in one place.
It’s easier to manage updates, passwords, and security.
Students can log in from any device and still access their own files.
Teachers can control who sees or edits each resource.

What are the problems?

If the server fails, the network may stop working for everyone.
It costs more money to set up and needs IT experts to manage it.

Peer-to-Peer Networks: Everyone Helps

In a peer-to-peer (P2P) network, there is no central server. All devices are equal, and each one can share files, folders, or printers with others. Every computer is both a client and a server. This setup is often used in small homes, cafés, or when friends want to play or share things quickly.

Everyday Examples:

Sending a file using Bluetooth or Airdrop is peer-to-peer.
Connecting laptops together to play Minecraft LAN at home.
Sharing a folder directly between two computers using Wi-Fi.
A small office where all computers share one printer without a server.

Why some people prefer it:

It’s easy and cheap to set up—no special hardware or server is needed.
Great for small networks where only a few devices are used.

But there are limits:

Each device manages its own files and security—this can be messy.
If a device turns off, others can’t access its shared files anymore.
Harder to control or protect the network if it gets bigger.

Comparing Client-Server architecture with P2P architecture

Cloud Computing: A Modern Use of Client-Server

Cloud computing is a popular and powerful version of the client-server model. Instead of storing your files on one computer, you use the cloud, which means storing data on internet-connected servers in data centres—huge buildings filled with high-powered machines.

Real-Life Cloud Examples:

Google Docs: Your writing is saved automatically on Google’s servers.
Gmail: Your emails live online, not on your phone.
OneDrive / iCloud: Your homework and photos are backed up and can be opened from any device.
Netflix / YouTube: Videos are streamed to your device from servers across the world.

Why people use cloud services:

You can access your files from anywhere, on any device.
Files are backed up—if your laptop breaks, your work is still safe.
Easy to share and work together on documents in real time.
Updates and storage are managed by the cloud provider, not you.

Cloud computing wouldn’t work without the client-server model. You are the client. The cloud provider—like Google or Microsoft—is the server.

Revision Focus

Client-Server networks use central servers to store files, manage users, and provide services. Clients send requests, and the server responds.

- These networks are centralised, easy to manage, secure, and common in schools, offices, and cloud services.
- If the server fails, the whole network may stop working.

Peer-to-Peer (P2P) networks have no central server. All devices (peers) are equal and can share directly.

- These are decentralised, cheap, and easy to set up, but harder to manage and less secure.
- P2P networks are often used in homes or small offices for sharing files or printers.

Cloud computing is a real-world client-server system where files and apps are stored on internet-based servers (in data centres).

- Cloud services like Google Drive or Gmail offer access from anywhere, automatic backups, and easy sharing.

Lesson Flashcards

RED TASKS (do not use AI to answer these)

Comprehension Questions

Copy them into your WBK and then answer in complete sentences.

What is a network and why do devices use one?
What is the main difference between a client-server network and a peer-to-peer network?
In a client-server network, what does the server do?
What is a client in a network?
Why are client-server networks common in schools and businesses?
What might happen if the server in a client-server network goes offline?
Why are peer-to-peer networks often used in homes or small offices?
In a peer-to-peer network, how do devices share resources?
What are some challenges of using a peer-to-peer network?
What is cloud computing, and how is it related to the client-server model?
Give two examples of cloud services that use client-server networks.
What is a data centre and what does it do?
Why is it easier to manage security in a client-server network?
What is one advantage of peer-to-peer networks over client-server networks?
Explain one reason why cloud computing is useful for students and teachers.

Active Learning

Individual

What Is Cloud Computing?

✍ In your WBK:

Write a 5-sentence summary explaining what cloud computing is
Add 1 image showing a cloud-based app like Google Drive
Title the page: Lesson 4 Summary: Client-Server & Peer-to-Peer

Pair

Compare the Models

Search: “client-server vs peer-to-peer network”

✍ In your WBK:

Create a table with 2 columns:
- Client-Server: 2 pros, 2 cons, 1 example
- Peer-to-Peer: 2 pros, 2 cons, 1 example

Small Group (3-4)

Mini Debate: Which Is Better?

Search: “advantages of client-server and peer-to-peer”

✍ In your WBK:

Write 3 strong reasons for each model
At the bottom, write your group’s decision: Which model is best for school and why?

Exam-style Questions

(2 marks) State two advantages of using a client-server network.
(3 marks) Explain one difference between a peer-to-peer network and a client-server network.
(3 marks) Describe how a cloud storage service like Google Drive uses the client-server model.

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