Routers compare packets' [...] to entries in the routing table.

Routers are designed primarily to direct packets across networks based on the destination address contained within the packet. The routing table is a critical component of the router’s functionality, as it contains the network addresses and the appropriate output interfaces to which packets should be sent.

When a router receives a packet, it extracts the destination IP address to determine the best route for that packet. The routing table is then consulted to find the matching entry that corresponds to the destination IP address. Based on this entry, the router can make decisions about where to forward the packet, ensuring it reaches the appropriate destination.

While the source IP address, protocol type, and port number can be important in different contexts, such as in access control lists or for packet filtering, the routing process itself focuses specifically on the destination IP address to make forwarding decisions. Hence, correctly identifying the destination IP address is critical for effective routing.