Networking and Data Communication cheat sheet

Data communication and networks overview

• Networks exist to let separate devices share data, applications and hardware resources, enabling collaboration, centralised data management and communication at a scale and speed no standalone device could achieve.
• By scope, a PAN covers a few metres around one person, a LAN a single building or campus, a MAN a city, and a WAN a country or a global span.
• A workgroup is a peer-to-peer group with no central authority, each machine managing its own accounts; a domain is centrally managed by a domain controller that authenticates users and enforces policy, and suits larger, more secure environments.
• Simplex sends in one direction only (a broadcast radio signal), half-duplex in both directions but one at a time (a walkie-talkie), and full-duplex in both directions at once (a telephone call).
• Digital transmission is a discrete binary signal, more resistant to noise and easier to process, encrypt and compress than a continuously varying analog signal; wireless transmission trades the convenience of no cabling for greater exposure to interference and interception.