Internet Structure & Protocols

Watch first — Craig 'n' Dave

Craig 'n' Dave · Edexcel 1CP2Network Protocols

Key facts

HTTP — HyperText Transfer Protocol. Web page requests. Unencrypted.
HTTPS — HTTP Secure. Encrypted using TLS/SSL. For secure web transactions.
FTP — File Transfer Protocol. Transferring files between computers. Jun 2024 Q3(c)(ii): FTP.
SMTP — Simple Mail Transfer Protocol. Sending email from client to server.
POP3 — Post Office Protocol 3. Downloading email from server to device. Deletes from server.
IMAP — Internet Message Access Protocol. Syncing email — stays on server. Access from multiple devices.

Application layer — HTTP, FTP, SMTP, DNS. What the application needs.
Transport layer — TCP/UDP. Breaks data into packets, ensures delivery.
Internet/Network layer — IP addressing, routing between networks.
Link/Data link layer — physical transmission on local network (MAC addresses, Ethernet).
Data travels DOWN the layers at the sender, UP the layers at the receiver.

DNS (Domain Name System) — translates human-readable domain names (bbc.co.uk) into IP addresses (151.101.0.81)
IP address — unique identifier for a device on a network. IPv4 = 4 sets of numbers (e.g. 192.168.1.1). IPv6 = 128-bit hexadecimal.
Packets — data is broken into packets for transmission. Each contains: source IP, destination IP, sequence number, data payload, error checking.
Router — reads destination IP, uses routing table to send packet to next router on the best path.

Exam questions — 4 questions · 11 marks · from real 1CP2 past papers

1 markIMAP vs POP31CP2 Jun 2023 Q2(e) style

A student wants to access their emails from both a laptop and a smartphone. Which protocol is most suitable and why?

A SMTP — because it sends email between servers

B POP3 — because it downloads emails to the device

C IMAP — because emails stay on the server and can be accessed from multiple devices

D FTP — because it transfers files efficiently

1 markProtocol identification1CP2 Jun 2024 Q3(c)(ii)

A developer wants to allow users to upload files to a remote server. Which protocol should they use?

A HTTP

B SMTP

C FTP

D IMAP

2 marksRouter function1CP2 Jun 2023 Q2(h) style

Describe how a router directs data packets across a network to their destination. (2 marks)

Hint: Cover: what the router reads (destination IP) AND what it does with that information (routing table, next hop).

+20 XP

4 marksTCP/IP layers1CP2 Jun 2023 Q2(a) style

The TCP/IP model has four layers. Name the Transport layer and the Link layer, and describe the role of each. (4 marks)

Hint: Name the layer AND describe its role. Two layers × two marks each.

+40 XP