DNS Leak over IPsec

I have setup an ipsec tunnel on my mikrotik router with a vpn provider but noticed that I am still leaking DNS requests.

Does anyone know how I could troubleshoot this to force the tunnel to route UDP packets properly?

I have the same question about this issue. However, I believe the following documents(2) is the right direction to go.

http://forum.mikrotik.com/t/nordvpn-ikev2-eap-vpn-tunnel-dns-leak/135884/1