I am dealing with a client that has been down all yesterday as well as today with conflicting IP addresses. I worked with Microsoft and they were able to find the mac address of another device that was giving out DHCP. I have tried arp on various servers and could not find that mac even after pinging the broadcast address. I have tried this command: show ip arp vlan (vlan number) | include (mac address) and all that it can really tell me is what the originating port is. This lead me to two HP switches which also have the mac address but that list the trunk port as the originating source. I am getting absolutely no where with finding this. Please help!!!!