Problem: When using PrivateInternetAccess VPN on the host (Win8.1 x86 in this instance), everything works for a Win7 vbox guest. But an openSUSE Tumbleweed linux guest cannot resolve any DNS queries (access by ip address works) while using vbox NAT.
Very bad solution: Bridged mode works, but that sidesteps the VPN entirely.
Not ideal solution: Disable VPN's "dns leak protection" option, let udp dns queries sidestep the VPN.
Probably solution: Use VPN'S dns server ips directly in /etc/resolve.conf config file. Not sure why Win7 vm just works, but Linux vm needs special treatment. I suspect this has to do with something vbox driver does for each environment. Or maybe the Win guest is more dynamic about grabbing host dns ip address changes.