A computer sends an email to a server on another network.
Identify the information in a packet header that a router uses to decide where to send the packet.
Mark scheme
- A Destination IP address (1)
- The only correct answer is A. A router reads the destination IP address in a packet header to forward the packet towards its destination.
- B is not correct because a MAC address identifies a device on a local network and is not used to route packets across the internet
- C is not correct because the packet number is used at the destination to put the packets back into the correct order
- D is not correct because the source IP address shows where the packet came from, not where it is going
Example answers and how they were marked
Full marks1/1
A Destination IP address
Why: Selected the destination IP address, the header information a router reads to forward the packet (1).
No marks0/1
D Source IP address
Why: A near miss: the source address is in the header, but it shows where the packet came from, so it is not used to decide where the packet is sent.
No marks0/1
B MAC address
Why: Typical misconception reported by examiners: a MAC address identifies a device on a local network and is not used to route packets across the internet.