@Dashrender said:

What do you expect to happen? That DNS queries should all go to the DNS server provided by the VPN DHCP request?

That's the hope if it is working correct. The VPN client should set the IP address of the workstation with a VPN address and make the primary DNS entry be one that looks through the VPN to the AD DC / DNS server with internal resolution. If not, why not? If so, what IP gets returned. The right one? Or if the wrong one, why?