Netextender DNS servers not used in Windows 8
If you notice that the Netextender DNS server is not used to resolve DNS names please go to the command line interface and execute the following command:
ipconfig /all

If, like in the output above the PPP adapter is not at the top of the adapter list then the metric of that adapter has to be lowered so that the DNS from the PPP connection will take precedence.
To check the metric of all the adapters please issue the following command:
Netsh interface ip show interfaces

To make sure that the metric of the other adapter (in this case Ethernet0) is higher than the Netextender adapter, please go to the properties of the adapter à Internet protocol version 4 à properties à advanced and change the metric accordingly.

After the change is accepted the Netextender DNS adapter should be used as the primary DNS server.