I get this feeling this may be a stupid question, but…
arp-ping appears once in the wiki, and there is no explanation next to it, as if everybody should already understand what it does. Sorry, but I don’t.
In Winbox Tools / Ping, I can specify an interface and a MAC address instead of an IP address, and directly ping a device at layer 2, so it looks like arp-ping must be for doing something else – I just can’t figure out what.
arp-ping just does an arp lookup. So it’ll broadcast over the ethernet network asking who has the IP you specified. Since ARP is required for IP networks, it’ll never be blocked by a firewall. But as arp is in layer 2, you must specify the ethernet network (by selecting the interface) in which to do the arp-ping.
If two devices on your network have the same IP, both will respond to the arp-ping. With wireshark you’d be able to determine the mac of both devices.
I get it. Thank you!