In a classless environment, when a router needs to send a packet to a particular destination, it performs the following check in this order:
1. Is the destination address one of my connected interface addresses? If yes, use ARP for the address and then encapsulate the packet in an Ethernet frame and send it to the destination.
2. If no, do I have a route in my routing table for this destination address? If yes, use that route from the routing table and send the packet.
3. If no, check whether the gateway of last resort is set. If it is set, send the packet to the address mentioned in the gateway of last resort. (In Example 5-74, the packets will be sent to 184.108.40.206. If there is no gateway of last resort, the packet is dropped.)
Example 5-74 shows that the gateway of last resort is set to 220.127.116.11. This means that if a router does not have an entry in the routing table, it will send the packet to 18.104.22.168.
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