No way to control which dns zone is used

[mortenn]

I have a split DNS deployment where subdomain.example.com is a private dns zone and example.com is a public dns zone.
When I add a route for service.subdomain.example.com Caddy fails to add a record to subdomain.example.com, which is the wrong dns zone to attempt to update.

I was unable to find a setting for which zone to use, so this seems to not work at present.

[mortenn]

I also tried setting AZURE_DNS_ZONE_FQDN after reading the libdns readme, but it had no effect

[kurokobo]

Thank you for raising the issue. At this time, private DNS zone is not supported.

I may not fully understand the goals you want to achieve, but is your scenario that the CA performing the DNS-01 challenge is a private CA located on a VNet, rather than a public CA like Let's Encrypt?

[mortenn]

yeah, I don't want it to use the private dns zone, but it does because the private dns zone is x.y.z when the fqdn is foo.x.y.z
I managed to work around it by overriding the challenge url to foochallenge.y.z and add a cname for the real challenge url