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I have a confusion. if the router doesn't find a path to the destination in the routing table, will it forward the packet through all the interfaces?

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Routing tables usually have a default path. Packets that don't meet the longest match for any entry in the routing table are then forwarded through the default route. There also exists Proxy ARP which can help find destinations that aren't in it's local routing table. But definitely the router doesn't forward packets out all interfaces in case it can't find the destination, it just drops the packets, in which case you'd get a destination unreachable or timed out or some error depending on the situation.

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No, the router does not flood the packet on all the other interfaces. Because not finding a path means that the router does not even have a default route. In that case, the packet is dropped. Depending on configuration, an ICMP Destination Unreachable with the apppropriate code is sent to the IP source address to inform about the unreachable destination. Here are the codes: ICMPv4, ICMPv6.

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