Knowledge Organiser: Client-Server and Peer-to-Peer Networks

Client: A device that requests services or resources from a server
Server: A dedicated computer that provides services (files, websites, email) to clients
Client-server network: A network with a central server providing services to client computers
Peer-to-peer (P2P): A network where all computers are equal and share resources directly with each other
Single point of failure: A component whose failure causes the entire service to stop

Client-server: central server, clients request resources — used in schools and offices
Client-server advantages: central security, central backups, central management, access from any device
Client-server disadvantage: server is a single point of failure; expensive server hardware needed
P2P: all computers equal — both client and server simultaneously
P2P advantages: no single point of failure; cheap (no dedicated server needed); easy to set up
P2P disadvantage: no central security or backups; difficult to manage at scale
Examples of P2P: BitTorrent file sharing, home file sharing, LAN gaming

Why schools use client-server: Central user accounts (log in from any computer), central backups, central security management
Why P2P suits file sharing: Each downloader also uploads — more peers = more bandwidth = faster downloads
Key difference: Client-server has a dedicated server; P2P has no dedicated server — every peer shares equally
Scalability: P2P scales naturally (more peers = more capacity); client-server can bottleneck at the server

Saying P2P has no servers at all: In a pure P2P network every device acts as both client and server simultaneously — there is no dedicated central server, but all peers can serve data
Saying client-server has no single point of failure: The opposite is true — if the central server goes down, ALL clients lose access; this is a key disadvantage of client-server over P2P
Confusing client-server with the Internet model: Visiting a website uses a client-server model (your browser is the client, the web server responds) — but school networks also use client-server for user account and file management
Saying P2P is always illegal: P2P technology itself is legal — it is only illegal when used to share copyrighted content without permission; legitimate uses include software updates and legal file sharing

Client-Server & Peer-to-Peer, Knowledge Organiser