Dhcploc

Dhcploc.exe: DHCP Server Locator Utility

This command-line tool displays the DHCP servers active on the subnet. If it detects any unauthorized DHCP servers, it beeps and sends out alert messages. It also displays packets that it detects from DHCP servers; you can specify whether to display packets from all DHCP servers or only those from unauthorized servers.

http://technet.microsoft.com/pt-br/library/cc759117%28WS.10%29.aspx