I do have a DNS server in my LAN, with some records served to internal clients only. But the _acme-challenge record needs to be public for the DNS-01 validation to succeed.
The point was that you can obtain a certificate for a domain name without creating any records other than the _acme-challenge TXT record. I.e., that the domain might be completely empty all the time except for this record.
The point was that you can obtain a certificate for a domain name without creating any records other than the _acme-challenge TXT record. I.e., that the domain might be completely empty all the time except for this record.