What will a router do if a matching route is not present in the router table?

The router will drop the packet if no matching route is present. The router will not flood all active interfaces; only switches perform flooding in an attempt to discover the destination MAC address. Routers will not multicast the packet if no route is known. The router will not send the original packet back to the originating host; it will, however, send an ICMP destination network unreachable packet to the originating host.