If a router does not know how to forward a packet, what does it do?

If a router does not know how to forward a packet, what does it do?

• A. Forwards to a default route
• B. Drops the packet
• C. Broadcasts the packet
• D. Creates a new packet

Answer: (B)

The router makes a forwarding decision by looking up the destination in its routing table. If there is no entry that matches the destination network, the router cannot determine the next hop to reach it, so it drops the packet. Some devices may send back an ICMP Destination Unreachable message to the sender, but the primary action in the absence of a known route is to discard the packet to avoid sending it nowhere. If a default route existed, the router would forward the packet to that next hop, but with no forwarding path available, dropping is the correct behavior.

The router makes a forwarding decision by looking up the destination in its routing table. If there is no entry that matches the destination network, the router cannot determine the next hop to reach it, so it drops the packet. Some devices may send back an ICMP Destination Unreachable message to the sender, but the primary action in the absence of a known route is to discard the packet to avoid sending it nowhere. If a default route existed, the router would forward the packet to that next hop, but with no forwarding path available, dropping is the correct behavior.