KS3 · Computer Science

Client-server vs peer-to-peer

Your school network and your home Wi-Fi are both networks, but they're organised completely differently. Here's the trick: switch one computer off and watch what breaks.

Computer Science · Structure

Two ways to organise a network

Tap each computer to find out its job. Then look for the centre: one network has one, the other doesn't.

Client-serverPeer-to-peerrequest / responseshare directly

Tap any part of the diagram to see what it does.

Predict, then check

Picture the two networks you just explored.

At school, the only server is switched off. At the same moment at home, one of three peers, a laptop, is switched off too. What happens to everyone else?

Benefits and drawbacks: which model is it?

For each statement, tick the model it is true of. Then check your grid and read why.

Files can be stored and backed up in one place
Security, user accounts and access rights are controlled centrally
It usually needs specialist staff to set up and manage
It is cheaper and simpler to set up
Backups and security have to be managed on each computer separately
A computer can slow down while others are using its resources

Where would you typically find each model?

Pick a use, then the model it typically uses. Read why it belongs there.

Still to sort

Client-server (0)

A central server provides services to many clients.

Where the line is: If one computer provides services for everyone else, it's client-server.

Peer-to-peer (0)

Equal computers share directly, with no central server.

Where the line is: If nobody is in charge and each computer shares its own files, it's peer-to-peer.

5 of 5 still to sort.

Is it really a network?

Two friends connect their laptops so they can swap photos and use one printer. There is no server anywhere.

Which is closest to what you think right now?
How sure are you?

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

One question sorts them: is there a central server?

What you need to know

  • A network is two or more computers or devices connected so they can communicate and share data and resources, such as files, printers and an internet connection.
  • In a client-server network, servers provide services (storing files, handling logins, sending web pages or email). Clients send requests, and the server responds.
  • In a peer-to-peer network there is no central server. Every computer is a peer with equal status that can act as both client and server.
  • The key difference is whether there is a central server. The benefits and drawbacks of each model follow from that.

The big picture

A network is two or more computers or devices connected so they can communicate and share data and resources. In a client-server network, a central server provides services and the clients send it requests. In a peer-to-peer network there is no central server: every computer is an equal peer that can act as both client and server. The benefits and drawbacks of each model follow from that one difference.

Key points

1Client-server benefits: files are stored and backed up in one place, and security, user accounts and access rights are controlled centrally.
2Client-server drawbacks: servers are more expensive, usually need specialist staff, and if a server fails the clients lose access to its services.
3Peer-to-peer benefits: cheaper and simpler to set up, and it doesn't depend on a single server.
4Peer-to-peer drawbacks: files are spread across many computers, backups and security are managed on each one separately, a switched-off peer's files are unavailable, and a computer can slow down while others use its resources.
5Typical uses: client-server for schools, businesses and the web (your browser is a client); peer-to-peer for small home networks and some file-sharing.

Worked example

Problem

A small bakery has two laptops. The owners want to share a folder of recipes and one printer. Money is tight, and nobody at the bakery looks after computers. Which network model suits the bakery better, and what does it give up?

⚠ Watch out

Getting the roles the wrong way round. In a client-server network the CLIENT sends the request and the SERVER provides the service and responds, not the other way round.

🧠

Memory hook

Ask 'Who's in charge?' Client-server: one hub, many spokes, the server's in charge. Peer-to-peer: a circle of equals, nobody's in charge, so everybody does both jobs.

✓

Check yourself

Without looking back: name the two jobs a peer can do, then give one benefit and one drawback of each model and say where each one comes from.

Flashcards

(13)
What is a network?
Two or more computers or devices connected so they can communicate and share data and resources, such as files, printers and an internet connection.
What does a server do in a client-server network?
It provides services and resources, such as storing files, handling user logins, or sending web pages or email, and responds to clients' requests.
What does a client do in a client-server network?
It sends requests to a server, and the server responds.
What is a peer in a peer-to-peer network?
A computer with equal status to all the others, which can act as both a client and a server.
Why can a client-server network back up its files in one place?
Because the files are stored centrally on the server, so they can be backed up there.
Name three things a client-server network can control centrally.
Security, user accounts and access rights.
Give two costs of running a client-server network.
Servers are more expensive, and they usually need specialist staff to set up and manage.
In a client-server network, what happens if a server fails?
The clients lose access to that server's services.
In a peer-to-peer network, what happens when one peer is switched off?
That peer's files become unavailable; the other peers can still share with each other.
Why can a peer's computer slow down?
Other peers are using its resources, because it is acting as a server for them.
Which places typically use client-server networks?
Schools and businesses. The web works this way too.
How does the web use the client-server model?
Your browser acts as a client, requesting pages from web servers, which respond by sending them.
Where are peer-to-peer networks typically used?
Small home networks and some file-sharing.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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