Client-Server & Peer-to-Peer

Computer ScienceOCRGCSEUnit: 3.5 Fundamentals of Computer Networks
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The basics

The Two Ways to Organize Networks

The Two Ways to Organize Networks

Networks can be organized in two fundamentally different ways. Client-Server: one powerful central server provides services (files, applications, authentication) to many client computers - like a restaurant where waiters (clients) take orders from customers and fetch food from the kitchen (server). Peer-to-Peer (P2P): all computers are equal - they can BOTH request AND provide resources - like a potluck dinner where everyone brings food and everyone takes food. Schools and businesses use client-server. File sharing (BitTorrent) uses P2P!
Exam tip

Earn the mark scheme marks

Exam Tips - Client-Server vs P2P

Most common exam questions:

  • "What is client-server?" → Central server provides services to client computers
  • "Advantage of client-server?" → Central security/backups/management
  • "Disadvantage of client-server?" → Server = single point of failure / expensive
  • "What is P2P?" → All computers equal - share resources directly (no server)
  • "Advantage of P2P?" → No single point of failure / cheap (no server needed)
  • "Disadvantage of P2P?" → No central security/backups / hard to manage
  • "Why do schools use client-server?" → Central accounts (login anywhere) / central backups / easy management

Key facts to memorize:

Aspect Client-Server P2P
Structure Central server + clients All equal (peers)
Security Centralized (easy) Decentralized (hard)
Cost Expensive (server) Cheap (no server)
Failure Server = single point No single point

Common mistakes to avoid:

  • Forgetting "central" when explaining client-server benefits (central security, central backups)
  • Not mentioning server = single point of failure (KEY disadvantage!)
  • Thinking P2P means "no server at all anywhere" - P2P means no DEDICATED server
  • Missing that P2P computers are BOTH client AND server

Perfect exam answer:

"Explain why a school should use client-server networking" (4 marks):

Central user accounts - students can log in from any computer (1 mark).
Central security - access controls managed in one place (1 mark).
Central backups - all student work backed up to server (1 mark).
Easy management - IT staff can manage from server (1 mark).

Now try it yourself

Quiz · Question 1 of 16

In a client-server network, what is the role of the server?

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