Explain the main network topologies, with diagrams, advantages and disadvantages.

1. 1 · Open in two lines. A network topology is the layout of how computers and devices are connected. The choice affects cost, speed and reliability.
2. 2 · Draw the layouts. [Diagram: a bus line with devices, a star around a switch, a ring loop, and a mesh with many links]
3. 3 · Bus. All devices on one backbone cable. Cheap and simple, but a cable break stops the network and it slows as traffic grows.
4. 4 · Star. All devices linked to a central switch. Easy to add devices and find faults, but if the switch fails, all stop.
5. 5 · Ring. Devices in a closed loop, data passing round in one direction. Orderly, but one break can stop the ring.
6. 6 · Mesh and hybrid.
   • Mesh: many links, very reliable, but costly; n(n − 1) ÷ 2 links for a full mesh.
   • Tree/hybrid: stars joined together; suits large firms.
7. 7 · Sri Lankan business example. A bank uses star LANs in each branch, joined by a WAN with backup links so branches stay online if one route fails.
8. 8 · Close in one line. The best topology balances cost, reliability and the size of the organisation.

Scoring tip: Neat, labelled diagrams for each topology earn most of the marks.