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1 [3 Marks Total]
(a) Which statement best describes "layers" in network protocols? Tick one. [1]
A physical cable that connects different switches together.
A division of network functionality into self-contained sections.
A security measure that stops hackers entering a network.
The speed at which data travels across the network.
(b) Complete the TCP/IP layers diagram (Layer 3 and Layer 1). [2]
Layer 4
Application Layer
Layer 3
Layer 2
Internet Layer
Layer 1
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(a) A division of network functionality into self-contained sections. (1)

(b) Layer 3: Transport (1). Layer 1: Link (1).

Score yourself (Max 3):
2 [3 Marks Total]
Match each protocol to the layer it operates in.
HTTP
TCP
Ethernet
Transport Layer
Application Layer
Link Layer
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Transport: TCP (1)

Application: HTTP (1)

Link: Ethernet (1)

Score yourself (Max 3):
3 [4 Marks Total]
Scenario: Engineer works on Application Layer without worrying about Link Layer (cables). Explain two benefits of this "layering".
Benefit 1: Benefit 2:
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Benefit 1: Decomposition - Breaks complex problems into smaller pieces (1) so developers can focus on one area (1).

Benefit 2: Interoperability - Layers are self-contained (1) so changes in one layer (e.g. WiFi vs Cable) don't break others (1).

Score yourself (Max 4):
4 [4 Marks Total]
Data movement up and down the layers.
(a) Describe what happens to data as it moves DOWN the layers (before sending). [2] (b) Describe what happens to data as it moves UP the layers (upon arrival). [2]
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(a) Down (Encapsulation): Extra info/headers are added to data (1). E.g. IP addresses at Internet layer (1).

(b) Up (Decapsulation): Headers are removed (1). Original data passed up to application (1).

Score yourself (Max 4):
5 [4 Marks Total]
Extended Short Answer: Explain why a NIC manufacturer (Link Layer) doesn't need to know which browser (Application Layer) is being used.
✅ Mark Scheme

Key Points (Max 4):

  • Layers are independent.
  • Link Layer only deals with physical connections / MAC addresses.
  • It doesn't care about the data content.
  • Protocols ensure data passed down is always in a standard format (Interoperability).
Score yourself (Max 4):