Edexcel 1CP2 · GCSE Computer Science · ~12 min read · 🔒 Pro
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Quiz
What is a Network Topology?
A network topology describes the physical or logical layout of how devices are connected in a network. Edexcel requires knowledge of star and bus topologies.
Star Topology
All devices connect to a central switch or hub. Each device has its own dedicated connection to the centre.
If one cable fails, only that device loses connection — other devices are unaffected
Easy to add or remove devices
Fast and reliable performance
If the central switch/hub fails, all devices lose connection
Requires more cable than bus
Most common topology used in modern LANs
Bus Topology
All devices connect to a single central cable (the bus or backbone). Data travels along the backbone in both directions.
Simple and cheap to install (less cable)
If the backbone cable fails, the entire network goes down
Collisions can occur when multiple devices send data at the same time
Performance degrades with more devices
A terminator is needed at each end to absorb signals
Rarely used in modern networks
Star vs Bus Comparison
Feature
Star Topology
Bus Topology
Central component
Switch or hub
Backbone cable
Cable failure
Only one device affected
Whole network fails
Central failure
All devices lose connection
N/A (no central device)
Cost
More cable + switch cost
Less cable, no switch
Performance
Fast, dedicated connections
Slower, collisions possible
Scalability
Easy to expand
Harder to scale
Usage
Most modern LANs
Older/legacy networks
Switch vs Hub
The central device in a star topology can be a hub or a switch:
Device
Sends data to
Performance
Hub
ALL devices (broadcast)
Less efficient — causes unnecessary traffic
Switch
Only the intended device (unicast)
More efficient — reduces traffic
A switch is always preferred in modern networks.
Exam tip: A common question: "State one advantage and one disadvantage of a star topology." Key answer: advantage — if one cable fails, other devices are unaffected; disadvantage — if the central switch fails, all devices lose connection. Draw topologies if asked!
⚠️ Common Mistakes
Saying "if a cable fails in a star, the whole network goes down" — this is bus, not star
Forgetting that in a bus topology, a backbone failure kills the whole network
Not knowing what a terminator does in a bus topology (absorbs signals at the ends)
Confusing hub and switch — a switch is smarter, sending data only to the intended device
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Worksheet — 4.1b Network Topologies
8 Edexcel-style questions · instantly marked
Q1What is a network topology?[1]
✅ Mark scheme
A network topology is the physical or logical layout/arrangement of how devices are connected in a network [1].
Q2Describe the structure of a star topology.[2]
✅ Mark scheme
All devices connect to a central switch or hub [1]; each device has its own dedicated cable running to the central switch [1].
Q3State one advantage and one disadvantage of a star topology.[2]
✅ Mark scheme
Advantage: if one cable fails, only that device is affected — the rest of the network continues working [1]; Disadvantage: if the central switch fails, all devices lose connection [1].
Q4Describe what happens in a bus topology if the backbone cable breaks.[2]
✅ Mark scheme
If the backbone cable breaks, the entire network fails [1]; all devices lose the ability to communicate as there is no alternative path for data [1].
Q5Why is a switch preferred over a hub in a star topology?[2]
✅ Mark scheme
A switch sends data only to the intended device (unicast) [1]; a hub broadcasts data to all devices, causing unnecessary traffic and reducing efficiency [1].
Q6What is the purpose of a terminator in a bus topology?[1]
✅ Mark scheme
A terminator is placed at each end of the backbone cable to absorb signals and prevent them from bouncing back, which would cause data errors [1].
Q7A hospital is setting up a new network. Which topology would you recommend? Justify.[3]
✅ Mark scheme
Star topology [1]; because if one cable fails, only one device is affected meaning medical systems can continue working [1]; more reliable and faster performance with dedicated connections [1].
Q8State one advantage of a bus topology over a star topology.[1]
✅ Mark scheme
Bus topology is cheaper to set up as it requires less cable and no central switch [1].
Topic Quiz
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Mini Test — Network Topologies
Timed exam-style test.
⏱10:00
Section A — Multiple Choice [5 marks]
Q1In a star topology, all devices connect to:[1]
Q2What happens if the backbone cable fails in a bus topology?[1]
Q3A switch differs from a hub because:[1]
Q4Which topology requires more cable?[1]
Q5Most modern LANs use:[1]
Section B — Short Answer
Q6Compare star and bus topologies. Include what happens when a component fails, cost, and performance.[3]
Mark schemeStar: one cable fails = one device down; bus: backbone fails = whole network down [1]; star is more expensive (switch + more cable) [1]; star has faster performance with dedicated connections; bus has collisions [1]; bus is cheaper [1].
Q7Explain why a switch is preferred over a hub as the central device in a star topology.[2]
Mark schemeA switch sends data only to the intended device (unicast) [1]; unlike a hub which broadcasts to all devices, causing unnecessary traffic and reducing performance [1].