Let's Debug

Test result for www.internal.cz using http-01

A fatal issue occurred during the DNS lookup process for www.internal.cz/A.
DNS response for www.internal.cz/A did not have an acceptable response code: SERVFAIL
Fatal
No valid A or AAAA records could be ultimately resolved for www.internal.cz. This means that Let's Encrypt would not be able to to connect to your domain to perform HTTP validation, since it would not know where to connect to.
No A or AAAA records found.
Debug
The IANA public suffix is the TLD of the Registered Domain
The TLD for www.internal.cz is: cz
Debug
4 Certificates contributing to rate limits for this domain

Serial: 265118950095939794510143765372937027879209
NotBefore: 2020-05-04 08:39:00 +0000 UTC
Names: [internal.cz]

Serial: 388019438214662802666732820434061612313986
NotBefore: 2020-05-03 15:06:14 +0000 UTC
Names: [internal.cz]

Serial: 308449333942878607420466011555391420541751
NotBefore: 2020-05-03 14:59:17 +0000 UTC
Names: [internal.cz]

Serial: 318399164256684230430363442983185545932876
NotBefore: 2020-05-03 00:09:44 +0000 UTC
Names: [internal.cz]

Debug
The current status.io status for Let's Encrypt
Operational

Submitted May 4 23:18:45 2020. Sat in queue for 2ms. Completed in 7s. Hide verbose information.