Looking back at some notes i've been making while going along trying to learn for ICND1 (still very early days), I have this question which I found while trying to quiz myself
"If a router doesn’t know where to send data what 2 options does the router have?"
So my first response would be for it to sent an ARP request across that broadcast domain.
I'm thinking the second option may be to check the routing table for the next router, and then if no idea from that go to the gateway of last resort?
Or would it be to simply reject the data?