Allow Private IP lookup in default built-in DNS server

[eivaunquig]

I have a number of resources that are set as for example hostname.internal.domain.tld. They're on private IP ranges so 10.x.x.x or 192.168.x.x being accessed through VPN.

OPNSense's default DNS is internal using unbound and blocks this by default.

How can I allow access without disabling the built-in default DNS handler 'unbound'?