Network stations that use IP protocol require both a physical address and an IP address to transmit packets. In situations where the station knows only the network host IP address, the Address Resolution Protocol (ARP) lets you use the network station to determine a network host physical address by binding a 32-bit IP address to a 48-bit MAC address.
A network station can use ARP across a single network only, and the network hardware must support physical broadcasts. If a network station wants to send a packet to a host but knows only the host IP address, the network station uses ARP to determine the host physical address.
ARP response is enabled by default.