As we’ve learned before, the Address Resolution Protocol (ARP) is the process by which a known L3 address is mapped to an unknown L2 address . The purpose for creating such a mapping is so a packet’s L2 header can be properly populated to deliver a packet to the next NIC in the path between two end points . The “next NIC” in the path will become the target of the ARP request . If a host is speaking to another host on the same IP network, the target for the ARP request is the other host’s IP address . If a host is speaking to another host on a different IP network, the target for the ARP request will be the Default Gateway’s IP address . In the same way, if a Router is delivering a packet to the destination host , the Router’s ARP target will be the Host’s IP address. If a Router is delivering a packet to the next Router in the path to the host , the ARP target will be the other Router’s I...