Microsoft Certified Systems Engineer (MCSE) Question:

The address resolution protocol (ARP) is used to associate the 32-bit IP address with the 48-bit physical address, used by a host or a router to find the physical address of another host on its network by sending an ARP query packet that includes the IP address of the receiver. The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.