Topic 3 · Networks

Two or more devices that can exchange data. Whether wired or wireless, scale doesn't matter.

Personal Area Network. ~10 m. Phone + earbuds.

Local Area Network. ~100 m. Home/office/school. One organisation.

Metropolitan. Kilometres. Across a city.

Wide Area. Countries/global. The Internet is the largest WAN.

All devices → central hub/switch. Most common. Hub fail = network dead.

One shared cable. Cheap. One break kills all.

Loop. Predictable. One device down breaks ring.

Many connections. Redundant + expensive. Used in backbone routers.

Dedicated server provides services; clients request. Centralised. Single point of failure unless replicated.

Every peer = client + server. Decentralised. Resilient. BitTorrent, Bitcoin.

Hub = dumb broadcast. Switch = smart, within LAN (L2, MAC). Router = between networks (L3, IP).

Internet = the network. Web (HTTP/HTML) = one service that runs on it. Email, gaming also on the Internet.