A fatal issue occurred during the DNS lookup process for opendrg.org/A.
DNS response for opendrg.org/A did not have an acceptable response code: SERVFAIL
No valid A or AAAA records could be ultimately resolved for opendrg.org. 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.