Types of Networks and Topologies
A computer network connects two or more devices to share data and resources.
Types by size
| Network | Range | Example |
|---|---|---|
| PAN | Personal Area Network. About 10 m. | Bluetooth between phone and earbuds |
| LAN | Local Area Network. One building or campus. | Office, school, cyber cafe |
| CAN | Campus Area Network. | University |
| MAN | Metropolitan Area Network. A city. | Cable TV network |
| WAN | Wide Area Network. Countries and continents. | The Internet is the largest WAN |
Intranet: private network inside an organisation, using Internet technology. Extranet: intranet opened to selected outsiders (suppliers, partners). VPN: secure private tunnel over the public Internet.
Client-server: a central server serves many clients. Peer-to-peer (P2P): every computer is both client and server.
Transmission modes
| Mode | Direction | Example |
|---|---|---|
| Simplex | One way only | Keyboard, TV broadcast, radio |
| Half duplex | Both ways, one at a time | Walkie-talkie |
| Full duplex | Both ways together | Telephone, mobile call |
Topologies
| Topology | Layout | Facts |
|---|---|---|
| Bus | Single backbone cable | Cheap. If the backbone fails, the whole network fails. |
| Ring | Closed loop | Data travels in one direction. One break can stop the ring. |
| Star | All devices to a central hub or switch | Most common. Easy to add devices. Failure of the centre stops the network. |
| Mesh | Every device linked to every other | Most reliable, most costly. Links = n(n-1)/2. |
| Tree | Stars joined on a bus | Hierarchical. |
| Hybrid | Mix of topologies | Flexible. |
Example: a full mesh of 6 computers needs 6 × 5 ÷ 2 = 15 links.
Transmission media
- Guided (wired): twisted pair (UTP, STP; used in LAN), coaxial cable (cable TV), optical fibre (light signals; fastest, no interference, long distance).
- Unguided (wireless): radio waves, microwave, infrared, satellite, Bluetooth, Wi-Fi.
Standards
| Standard | Meaning |
|---|---|
| IEEE 802.3 | Ethernet |
| IEEE 802.11 | Wi-Fi (versions 802.11 a, b, g, n, ac, ax; Wi-Fi 6 is 802.11ax) |
| IEEE 802.15 | Bluetooth |
| IEEE 802.16 | WiMAX |
Keep practising
Notes are only half the work. Test yourself with questions and discuss doubts with other aspirants.
Prepared for exam revision from standard computer textbooks, Microsoft documentation and official sources. Features differ between Excel and Word versions (2016, 2019, 2021, 365) so check which version your exam follows. Found a mistake? Tell us.