We just pushed an update live that will allow you to configure CleanBrowsing to act as an “authoritative” server for your local/internal domains.
If you visit our DNS Mapping section here:
You will be able to add your local domains and point them to internal IPs. For example:
corporate.lan -> 10.1.1.1
printer.lan -> 10.1.1.2
fileserver.local -> 192.168.1.1
And similar entries. Both internal and external IP addresses can be used.
Try it out and let us know how it goes.