In IB Computer Science, students are expected to understand not only how devices are connected, but how roles are distributed within a network. This is explained using two fundamental network models: client-server and peer-to-peer (P2P).
These models describe how data, services, and control are organised, and they appear frequently in exam questions that ask students to compare, justify, or apply networking concepts.
What Is a Client-Server Network?
In a client-server network, roles are clearly defined.
- Clients request services or resources
- Servers provide services or resources
The server is usually a powerful, dedicated machine that:
- Stores data
- Manages access
- Handles requests from multiple clients
Clients depend on the server to function properly.
How Client-Server Networks Work
When a client needs data:
- The client sends a request to the server
- The server processes the request
- The server sends the requested data or service back
This centralised control allows:
- Efficient management
- Strong security
- Consistent data access
Common real-world uses include:
- School or office networks
- Web hosting
- Email systems
Advantages of Client-Server Networks
Client-server networks offer:
- Centralised data storage
- Easier backups
- Strong access control
- Better security management
- Consistent performance
These advantages make client-server networks suitable for medium to large organisations.
Disadvantages of Client-Server Networks
However, they also have limitations:
- Higher setup and maintenance cost
- Requires skilled administration
- Server failure can disrupt the entire network
In IB exams, this is often described as a single point of failure.
What Is a Peer-to-Peer Network?
In a peer-to-peer (P2P) network, all devices have equal roles.
Each device:
- Can request data
- Can provide data
There is no central server. Devices communicate directly with each other.
How Peer-to-Peer Networks Work
In a P2P network:
- Devices share files directly
- Resources are distributed
- Each peer manages its own data
This model is commonly used in:
- Small home networks
- Temporary networks
- File-sharing systems
Advantages of Peer-to-Peer Networks
Peer-to-peer networks offer:
- Low cost
- Simple setup
- No dedicated server required
- No single point of failure
They are ideal for small-scale or informal networks.
Disadvantages of Peer-to-Peer Networks
However, they also have drawbacks:
- Weak security
- No central control
- Difficult to manage as the network grows
- Data inconsistency
As the number of devices increases, performance and organisation can degrade.
Comparing Client-Server and Peer-to-Peer Networks
Strong IB answers compare the models clearly:
- Client-server
- Centralised control
- Better security
- Higher cost
- Peer-to-peer
- Decentralised
- Lower cost
- Limited scalability
The key difference is control and responsibility.
How This Appears in IB Exams
Students may be asked to:
- Compare the two models
- Choose a suitable model for a scenario
- Justify network design decisions
- Discuss security and scalability
Justification is more important than memorisation.
Common Student Mistakes
Students often:
- Say peer-to-peer networks have servers
- Ignore scalability issues
- Forget security implications
- Give one-sided comparisons
Balanced explanations score higher.
Final Thoughts
Client-server and peer-to-peer networks represent two very different ways of organising network communication. Client-server networks prioritise control, security, and scalability, while peer-to-peer networks prioritise simplicity and cost.
Understanding when and why each model is used allows IB Computer Science students to analyse real-world networks accurately and confidently.
