Spec & Goals 3 min
AQA Spec 3.5.2 — Network protocols: Ethernet, Wi-Fi, TCP, UDP, IP, HTTP, HTTPS, FTP, SMTP, IMAP
By the end of this lesson you can:
- Define a protocol and explain why protocols are needed.
- State the purpose of TCP, IP, HTTP, HTTPS, FTP, SMTP and IMAP.
- Choose the correct protocol for a given task.
Warm-Up 5 min
Two strangers can only talk if they share a language and rules of conversation. Computers are the same — their shared rules are called protocols.
Quick starter
You've seen http and https at the start of web addresses. What do you think the extra s stands for, and why does it matter?
Reveal the idea
The s is for secure — HTTPS encrypts the data so it can't be read if intercepted. Crucial for passwords and online banking.
Key Concept — the rules of communication 14 min
A protocol is a set of rules that lets devices communicate. Both ends must follow the same protocol — agreeing the format, order and error-checking of the data.
The protocols AQA expects you to know
| Protocol | Stands for | Purpose |
|---|---|---|
| TCP | Transmission Control Protocol | Splits data into packets and reassembles them in order at the other end; checks none are lost. |
| IP | Internet Protocol | Addresses and routes packets across networks to the right destination. |
| UDP | User Datagram Protocol | Faster than TCP but without delivery/order guarantees (e.g. live video). |
| HTTP | HyperText Transfer Protocol | Transfers web pages between a web server and a browser. |
| HTTPS | HTTP Secure | HTTP with encryption — secures web data (banking, logins). |
| FTP | File Transfer Protocol | Transfers (uploads/downloads) files between computers. |
| SMTP | Simple Mail Transfer Protocol | Sends email to a mail server / between mail servers. |
| IMAP | Internet Message Access Protocol | Receives / reads email, keeping it stored on the server. |
| Ethernet | — | The set of rules for connecting devices on a wired LAN. |
| Wi-Fi | — | The set of rules for connecting devices wirelessly on a LAN. |
Worked Example — pick the protocol 12 min
Problem: Name the most suitable protocol for each task and say why.
| Task | Protocol | Why |
|---|---|---|
| Loading a school's public website | HTTP | Transfers web pages to the browser (no sensitive data). |
| Logging in to online banking | HTTPS | Encrypts the login so it can't be read if intercepted. |
| Uploading photos to a web server | FTP | Designed for transferring files between computers. |
| Sending an email to a friend | SMTP | SMTP sends mail to / between mail servers. |
| Reading email already in your inbox | IMAP | Retrieves/reads mail while keeping it on the server. |
Underneath all of these, TCP/IP does the work: TCP breaks the data into packets and reassembles them; IP routes each packet to the right place.
Try It Yourself 12 min
Goal: Write what each stands for: HTTP, HTTPS, FTP.
Goal: State the difference between SMTP and IMAP.
Hint: one sends, one receives.
Goal: Explain the role of TCP and the role of IP when a web page is sent across the internet.
📝 Exam Practice 10 min
Define the term protocol.
Mark scheme
- A set of rules (for how devices communicate / for data transmission) (1).
State the purpose of (a) HTTPS and (b) FTP.
Mark scheme
- (a) HTTPS — securely transfers web pages / HTTP with encryption (1).
- (b) FTP — transfers (uploads/downloads) files between computers (1).
Explain why HTTPS rather than HTTP should be used for online shopping.
Mark scheme
- It encrypts the data sent between browser and server (1).
- So payment/personal details can't be read/used if intercepted (1).
Identify the protocol used to send an email.
Mark scheme
- SMTP (Simple Mail Transfer Protocol) (1).
Recap & Key Terms 3 min
A protocol is the agreed set of rules for communication. TCP splits and reassembles data; IP routes it. HTTP/HTTPS carry web pages (HTTPS encrypted); FTP transfers files; SMTP sends email and IMAP receives it.
- Protocol
- A set of rules that governs how devices communicate across a network.
- TCP / IP
- TCP splits data into packets and reassembles them in order; IP addresses and routes the packets.
- HTTP / HTTPS
- Transfer web pages between server and browser; HTTPS adds encryption for security.
- SMTP / IMAP
- SMTP sends email; IMAP receives/reads it while keeping it on the server.
Homework 1 min
Task (≤ 15 min): Make a quick-reference table of these seven protocols — TCP, IP, HTTP, HTTPS, FTP, SMTP, IMAP — with one short sentence on the purpose of each.
Model answer
TCP — splits data into packets and reassembles them in order. IP — addresses and routes packets to the destination. HTTP — transfers web pages to a browser. HTTPS — HTTP with encryption for security. FTP — transfers files between computers. SMTP — sends email. IMAP — receives/reads email kept on the server.
Award marks for: each correct purpose (up to 7); SMTP/IMAP send vs receive distinction made correctly.