I ammend my previous reply slightly. If ICMP Blocking is turned on, the ARP request will still go out. however, I still find that I cannot rely on the ARP cache as the source of my information, especially as in Linux the only way to reliably clear an arp cache is to bring the interface down and back up. So in the end, I still feel that dealing with a raw ARP Request and Reply over the wire is the best way to accomplish my ends. Thank you though.