Client-Server and Peer-to-Peer Networks

This lesson covers the two main network models — client-server and peer-to-peer (P2P) — as specified in OCR J277 Section 1.3.1. You need to understand how each model works, its advantages and disadvantages, and when each is appropriate.

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Client-Server Networks

What Is a Client-Server Network?

In a client-server network, there is one or more central servers that provide services and resources to multiple clients (user devices). The server manages shared resources and controls access.

How It Works

Component	Role
Server	A powerful computer that stores files, manages access, runs services (email, web, print), and controls security
Client	A user's computer that requests services or data from the server

Process:

1. A client sends a request to the server (e.g. "I want to open my file").
2. The server processes the request (e.g. checks permissions, locates the file).
3. The server sends a response back to the client (e.g. the requested file).

Types of Server

Server Type	Function
File server	Stores and manages shared files
Print server	Manages print jobs sent to shared printers
Email server	Sends, receives, and stores emails
Web server	Hosts websites and serves web pages
Database server	Manages shared databases
Authentication server	Manages user login credentials and access permissions

Advantages of Client-Server

Advantage	Explanation
Centralised management	Files, users, and security are managed from one place
Centralised backup	The server can be backed up regularly and automatically
Security	User permissions and access rights are controlled centrally
Scalability	New clients can be added easily
Resource sharing	Printers, files, and internet connections are shared efficiently

Disadvantages of Client-Server

Disadvantage	Explanation
Cost	Servers are expensive to buy and maintain
Specialist staff	A network administrator is needed to manage the server
Single point of failure	If the server fails, all clients lose access to shared resources
Congestion	If too many clients request services simultaneously, the server may slow down

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Peer-to-Peer (P2P) Networks

What Is a Peer-to-Peer Network?

In a peer-to-peer network, there is no central server. Every device (called a peer or node) is equal — each device can act as both a client and a server, sharing its own files and resources directly with other devices.

How It Works