Appnr

Tool to send ARP Requests for an IP address

The standard ping command sends ICMP Echo Requests to an IP address.
To do that on an Ethernet-type link, however, the sending node needs
to know the MAC address of the destination, so when standard ping
fails, you don't really know whether it is the address resolution or
the Echo Request that fails.

The arping command only does the ARP part, so it can be useful after
a failed ping in figuring out whether it is the resolution or the
ICMP Echo that fails. It can do other useful things, too.