Identify the purpose of the packet number in a data packet.
Mark scheme
- C To reassemble the packets in the correct order (1)
- The only correct answer is C. The correct answer is To reassemble the packets in the correct order.
- A is not correct because error checking uses the error checking data in the packet, not the packet number
- B is not correct because the destination IP address identifies the destination device, not the packet number
- D is not correct because routers use the destination IP address to choose the route, not the packet number; routers may briefly buffer packets but do not use the packet number to store them
Example answers and how they were marked
Full marks1/1
C To reassemble the packets in the correct order
Why: Selected the purpose of the packet number, which allows the packets to be reassembled in the correct order (1).
No marks0/1
D To select the fastest route for the packet
Why: A near miss: routers choose routes using the destination IP address, so this does not describe the purpose of the packet number.
No marks0/1
B To identify the destination device
Why: Misconception: the destination IP address identifies the destination device, not the packet number.