' From the book "Windows XP Cookbook"
' ISBN: 0596007256

' This code performs a query for all DHCP enabled IP addresses and releases
' them.  Use this instead of the other example if you want to tailor the 
' query to return a subset of connections. Modify the WQL statement based
' on your criteria.
' ------ SCRIPT CONFIGURATION ------
strComputer = "."
' ------ END CONFIGURATION ---------
set objWMI = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
set colNetworkAdapters = objWMI.ExecQuery _
 ("Select * From Win32_NetworkAdapterConfiguration Where DHCPEnabled = True")
for each objNetworkConfig in colNetworkAdapters
 intRC = objNetworkConfig.ReleaseDHCPLease()
 if intRC = 0 then
   WScript.Echo "Released IP address for " & objNetworkConfig.Description
 elseif intRC = 1 then
   WScript.Echo "You must reboot to release the IP address for " & _
   objNetworkConfig.Description
 else
   WScript.Echo "There was an error releasing the IP address for " & _
   objNetworkConfig.Description & ": " & intRC
 end if
next