This topic summary covers Knowledge Organiser: Network Topologies within Network Topologies for GCSE Computer Science. Revise Network Topologies in 3.5 Fundamentals of Computer Networks for GCSE Computer Science with 16 exam-style questions and 18 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Network Topologies
Key Terms
- Network topology: The physical or logical arrangement of devices in a network
- Star topology: All devices connect to a central switch or hub
- Mesh topology: Devices connect to multiple other devices providing redundant paths
- Bus topology: All devices connect to a single backbone cable (largely obsolete)
- Single point of failure: One component whose failure causes the entire network to fail
- Redundancy: Having alternative paths so the network continues if one link fails
Must-Know Facts
- Star topology: all devices connect to a central switch — most common in homes, offices, schools
- Star advantage: one cable break = only that device affected (isolated failures)
- Star disadvantage: central switch is a single point of failure
- Mesh advantage: no single point of failure — data finds alternative routes
- Mesh disadvantage: very expensive (many cables) and complex to manage
- Bus and ring topologies are largely obsolete — modern networks use star
- Mesh used only for critical systems (data centres, ISP backbone)
Key Concepts
- Star vs mesh trade-off: Star is cheaper with one point of failure; mesh is expensive with no single failure point
- Why star dominates: Easy to add devices, easy to troubleshoot, isolated failures, cost-effective
- Why mesh is rare: n devices need n(n-1)/2 connections — 1000 devices = 499,500 cables!
- Bus failure mode: Any break in the backbone cable = entire network fails
Common Mistakes
- Saying the switch is the "single point of failure" in a star topology: The central switch failing brings down the whole network — but individual device failures do NOT affect others; be precise about which failure point is meant
- Confusing physical and logical topology: Physical topology is how cables are physically laid out; logical topology is how data flows — a network can look like a star physically but behave differently logically
- Saying mesh topology is "better" without justification: Mesh provides redundancy but is extremely expensive and complex — always weigh cost and complexity against reliability in exam answers
- Forgetting bus topology weaknesses: In a bus topology, all devices share one cable so collisions occur and any cable break stops the entire network — it is largely obsolete but still tested
Practice questions for Network Topologies
In a star network topology, all devices connect to which central component?
State two advantages of a mesh network topology. [2 marks]