RESOLVE errors after vpn tunnel goes down

[foormanek]

Hello,
When openvpn tunnel to PIA or Vpnunlimited first goes up, it works. When tunnel goes down and tries to reinitialize, it gets
RESOLVE: Cannot resolve host address:
errors. Obviously it tries to resolve dns trough its own tunnel being down, which is futile. I have kind of solved this before putting numerical IP of vpn access point instead of a name into vpn config, but this does not work for long, these IP do change.

What is the best way to make OpenVpn always successfully resolve dns, and at the same time guarantee, that connected clients use dns resolving trough a vpn tunnel?