The OVPN client holds a functionality to ensure that no DNS leaks occur. The client changes the settings of all available network adapters on your device so that your computer uses OVPN’s DNS servers, which are configured to not store any information.
In addition to changing DNS servers, the client also constantly checks the DNS settings every second so that they aren’t changed while connected to OVPN. If at any point they are changed, the client changes them back to the correct and safe ones.
This functionality helps make sure you are not connected to unsafe DNS servers as well as prevent you from being subject to a network attack.
Prevent DNS leaks can be activated/inactivated from the Account tab in the client.