Just spent 15 minutes tracking down a phantom machine on my home DHCP network. I was working on my wifes laptop figuring out why it had lost it’s IP again and wouldn’t renew. I checked my DHCP server and noticed one too many machines had addresses. I deleted the IP from DHCP but it came right back! I couldn’t access it or find anything out about it. A Traceroute to the IP took 1500 mils… yow that can’t be in my house!! I quickly inventoried all my computers in my head and matched them against my DHCP list, yep one too many.
So I went to this site and queried the MAC address to see who the manufacturer was. Nintendo?! before I could mouth WTF I realized it was our new Nintendo Wii online in the basement… what a dork.