There seems to be some DHCP funnyness going on so I need to run something to show me what's going at a DHCP level. Before I upgraded my machine to Windows 7 I used DHCPloc.exe from the Windows XP support tools, and it worked like a charm.
I can't seem to find Support Tools for Windows 7, and trying to use the XP tools in compatibility mode doesn't work (I tried, it fails to open a receiving socket).
I need a tool to monitor DHCP traffic, and ideally one that lets me filter it to exclude DHCP traffic from our trusted DHCP servers and only show me un-authorised DHCP traffic.
You can still use DHCPloc.exe on Windows 7:
DHCPLoc.exe works fine on my Win7 x64 installation.
Since DHCP traffic is broadcast based you should be able to run a packet capture somewhere on your network and see it. Try installing Wireshark or Microsoft Network Monitor on your Windows 7 machine, start a capture, and filter for DHCP traffic.
You can use this technique to open DHCPLoc.exe on newer Windows versions.
Download "Windows XP Service Pack 2 Support Tools" from [here][1].
Open the downloaded file - WindowsXP-KB838079-SupportTools-ENU.exe - using 7-zip.
DHCPLoc.exe is contained within the "support.cab" file.