Client-Server Networks
In a client-server network, dedicated servers provide services (files, email, web pages) and clients request them. The server is always on and manages resources centrally.
- Server controls resources and security (user accounts, access rights)
- Backups are centralised and managed
- Easier to manage for large networks
- If server fails, clients lose access to services
- Requires dedicated, expensive server hardware
Peer-to-Peer (P2P) Networks
In a peer-to-peer network, all computers are equal — each can act as both client and server, sharing resources directly with others.
- No central server required
- Cheaper to set up (no dedicated server)
- Each computer manages its own security and backups
- Performance decreases as more peers share resources
- Hard to manage for large networks
- Examples: file sharing networks, some small home networks
| Feature | Client-Server | Peer-to-Peer |
|---|
| Central server | Yes | No |
| Cost | Higher (server hardware) | Lower |
| Security | Centralised, managed | Each device manages its own |
| Backup | Centralised | Each device backs up itself |
| Scalability | Good for large networks | Suitable for small networks |
| If server fails | All clients lose service | Other peers unaffected |
IP Addresses
An IP address is a logical address that identifies a device on a network. It can change (e.g. when you reconnect to Wi-Fi).
- IPv4: 32-bit address written as 4 decimal numbers (e.g. 192.168.1.10). Around 4 billion unique addresses.
- IPv6: 128-bit address written in hexadecimal (e.g. 2001:0db8::1). Needed because IPv4 addresses ran out.
- IP addresses are used by routers to route packets across networks
MAC Addresses
A MAC (Media Access Control) address is a physical address permanently assigned to a network interface card (NIC) by the manufacturer. It cannot normally be changed.
- 48-bit address written in hexadecimal (e.g. 00:1A:2B:3C:4D:5E)
- Unique to each network interface card
- Used within a local network (switches use MAC addresses to direct traffic)
- Does not change when you move between networks
| Feature | IP Address | MAC Address |
|---|
| Type | Logical | Physical |
| Assigned by | Network (DHCP/manual) | Manufacturer |
| Can change? | Yes | No (normally) |
| Used for | Routing across networks | Delivery within a LAN |
| Format (example) | 192.168.1.1 | 00:1A:2B:3C:4D:5E |
Exam tip: The key distinction is IP = logical (can change, used for routing) vs MAC = physical (permanent, used on local network). Cambridge also commonly asks you to compare client-server vs P2P — know at least 2 differences with advantages/disadvantages of each.
⚠️ Common Mistakes
- Saying MAC addresses can change — they are permanently assigned by the manufacturer
- Confusing when IP vs MAC addresses are used — IP is for routing between networks; MAC is for delivery within a LAN
- Saying P2P has no security — it does, but each device manages its own (there's no central authority)