6.3. Delegation to Private Nameservers

6.3 Delegation to Private Nameservers

Some FQDN administrators make the contents of a subdomain unresolvable on the public Internet by delegating that subdomain to a nameserver whose IP address is private. A CA processing CAA records for such subdomains will receive SERVFAIL from its recursive resolver. The CA MAY interpret that as preventing issuance. FQDN administrators wishing to issue certificates for private FQDNs SHOULD use split-horizon DNS with a publicly available nameserver, so that CAs can receive a valid, empty CAA response for those FQDNs.