For setting up a complex network scenario with split DNS it would be good if you could set also an NXDOMAIN entry/checkbox for IPv4 or IPv6.

Example:

Internally I want to have clients only connect to a specific service via IPv4, not via IPv6. Then I put in the DNS host entry for IPv4 and for IPv6 I set NXDOMAIN. Because if there is an external IPv6 entry the XG will deliver this one back as it can't resolve it internally.

Also this is a big problem if the external DNS host entry is a CNAME because it resolves the external CNAME (if there is set only IPv4 OR IPv6 as the manual dns host entry), too. After delivering this CNAME to a Windows DNS this one overwrites the already resolved IP address for Split DNS functionality...