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The Four-Layer Network Stack
The Four-Layer Network Stack
When you send data across the Internet, it doesn't just magically appear at the destination. It passes through four distinct layers, each with a specific job. The TCP/IP model divides network communication into these layers: Application (what you see), Transport (reliable delivery), Internet (routing), and Link (physical transmission). Think of it like sending a letter: you write the message (Application), put it in an envelope with address (Transport), the postal service routes it (Internet), and it's physically carried by van/plane (Link)!
Layer 4: Application Layer
What happens here: This is where network applications and protocols operate - the layer you interact with directly.
Earn the mark scheme marks
Exam Tips - TCP/IP Layers
Key facts to memorize:
- 4 layers: Application, Transport, Internet, Link (top to bottom)
- Application: HTTP, SMTP, FTP - what you interact with
- Transport: TCP (reliable) or UDP (fast) - error checking
- Internet: IP addresses, routing
- Link: MAC addresses, physical transmission
- TCP vs UDP: TCP=reliable (checks errors), UDP=fast (no checking)
Perfect exam answer:
"Describe the four layers of the TCP/IP model" (4 marks):
Application: Network services/protocols like HTTP (1 mark).
Transport: Reliable delivery using TCP/UDP (1 mark).
Internet: Routing using IP addresses (1 mark).
Link: Physical transmission over network hardware (1 mark).
Now try it yourself
Quiz · Question 1 of 16
How many layers does the TCP/IP model have?
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This topic in real past papers
Every real exam question we've found on tcp/ip layers, with a full worked answer.