So basically we would like that if 2 subdomains redirect to the same IP address for example sub1.example.com and sub2.example.com redirect to 1.2.3.4. the firewall handles the request and redirects to an internal IP address.
Example:
sub1.example.com->1.2.3.4(external)->DNS->10.1.100.1(internal)
sub2.example.com->1.2.3.4(external)->DNS->192.168.0.1(internal)
A better illustration is shown in the image below:
How can this be achieved from a firewall that uses BIND 9 dns module?
Just a note: The firewall is Zentyal.