Protocols, Layers and the Internet
What a protocol is
A set of rules allowing devices to communicate.
Common protocols
| Protocol | Use |
|---|---|
| TCP/IP | Splits data into packets and routes them |
| HTTP / HTTPS | Web pages (HTTPS is encrypted) |
| FTP | Transferring files |
| SMTP | Sending email |
| IMAP / POP | Receiving email |
Packet switching
Data is split into packets, each with the destination address and a sequence number. Packets travel by the best available route and are reassembled in order at the destination.
Why use layers?
Networking is split into layers, each doing one job. Benefits:
- Each layer can be developed/changed independently.
- Easier to understand, build and maintain.
- Equipment from different manufacturers can work together.
The internet
A global WAN. DNS translates domain names (e.g. bbc.co.uk) into IP addresses. Web content may be hosted on the cloud (remote servers).
Exam tip
"Why split networking into layers?" → each layer is self-contained and can be modified without affecting the others. Know SMTP = send, IMAP/POP = receive.