This happens mainly with routed connection. So we should By-pass the routes then only we can solve this problem.
How to Bypass Routes on Ubuntu:
to ignore automatically obtained routes on Ubuntu you need to edit the network connection setting, To do,
you can access 'Network Connections' by System=> Preference's=> Network Connections
or directly Right-clicking and select Edit Connections in network icon on system tray.
Now it will open Network Connections, Now navigate tab which connection type you are using and click Edit.
It will open new window named 'Editing your Connection name'. In that window go to IPv4 Settings.
Select method type to Automati (ppp) address only and then enter your DNS server addresses. I have entered open DNS servers 188.8.131.52, 184.108.40.206 . and then click 'Routes' button
Then click ignore automatically obtained routes. and click ok on all windows to save this new setting.
Thats it! :)
[ If you have any suggestions post as comment ]