Computing - Topologies
AQA Computer Science 2022
See Also
Networks and topologies
What is a computer that is not connected to any other devices called?
A standalone computer.
What is a Local Area Network?
Two or more computers connected together within a small geographical area.
What is a bus network?
An arrangement where nodes are connected in a daisy chain by a single central communications channel.
What is a star network?
An arrangement where a central node or hub provides a common connection point for all other nodes.
In a bus network, what is the main limitation of how data can be sent?
It can only be sent in one direction at a time only.
In a bus network, why can only one computer transmit data successfully at a time?
Because otherwise you’d get data collisions.
CSMA/CD and collisions
What does CSMA/CD detect?
When two nodes are attempting to transmit data simultaneously.
How does CSMA/CD prevent nodes transmitting data simultaneously?
Both nodes cease transmission and wait a random amount of time before reattempting.
NICs, MAC addresses and switches
How does a switch know which device to send packets to?
It stores the MAC addresses of the devices on the network.
Why is a switch more secure than a hub?
Because it doesn’t send every packet to every device.
Physical vs logical topology
What is the physical topology of a network?
How the devices are physically connected.
What is the logical topology of a network?
How the devices communicate across the physical topologies.
How could you make a physical star network behave as a logical bus network?
Using a bus protocol and physical switching.
What is the logical topology of the three computers on the left?
What is the logical topology of the three computers on the left?A bus network.