If a router receives a packet whose IP destination address is not in its routing table, I believe it will send it to its default port.
Suppose that we erase that entry from the table. Now, I think that the router will send an ARP request in order to find where to forward it. I have two questions regarding this process:
- If there is no ARP response (i.e. there is no route from the router to the destination address), will it discard it and send an ICMP message to the origin stating that the destination was unreachable?
- Will in any case a router discard a packet just because the destination address is not in its routing table (assuming there is no 'default' entry)? Or will it always check if it is possible to reach the destination via ARP requests?