Routers forward data across the internet.
Explain how a router uses the destination IP address of a packet to send the packet towards its destination.
Mark scheme
Award up to two marks for a linked explanation such as:
- The router reads/checks the destination (IP) address in the packet (1) so it can forward/send the packet towards that address/destination (1)
- The router looks up/compares the destination (IP) address (1) to choose the route/next network/next router for the packet (1)
- The router uses the destination (IP) address to choose/select the outgoing connection/network (1) so the packet is sent one step closer to its destination (1)
For both marks, the expansion must follow/associate with the statement.
Do not accept a restatement of the question, such as 'the router uses the IP address to forward the packet', without saying how the address is used, e.g. checking the destination address or choosing the route/next network.
Do not accept answers that say the router gives/adds an IP address to the packet, or that the router uses a MAC address instead of the destination IP address.
Example answers and how they were marked
The router checks the destination IP address in the packet and sends the packet out on the route/network that leads towards that address.
Why: Point (1): the router checks the destination IP address; linked reason (1): this is used to send the packet towards that destination.
The router checks the destination IP address in the packet.
Why: Point (1): the router checks the destination IP address; no linked reason is given, so only the first mark.
It adds an IP address to the packet so the packet knows where to go.
Why: Misconception: the router does not add an IP address to the packet; the mark scheme says not to accept this, so no marks.