This trick didn't work under Windows 8.1. Instead I had to following the instructions found at http://support.microsoft.com/kb/311218.
Click Start, click Run, type regedit32 in the Open box, and then click OK. Click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Linkage In the right pane, double-click Bind. In the Value data box, select the "\Device\NdisWanIp" item, press CTRL+X, click the top of the list of devices, and then press CTRL+V. Click OK, and then quit Registry Editor.
The device GUID for the VPN adapter on my system was \Device\
(I only found that by trail an error). When I put that at the top of the list, my DNS queries worked once the VPN cpnnection was established.