The RFC wording is a little weird. If the zone has DNSSEC configured, then the wording should be stronger and use MUST wording, and not imply that CAs will be compliant if they choose to avoid verifying signatures despite the presence of signstures. Likewise, these TXT records for dns-persist-01 ideally "SHOULD NOT" be deployed when DNSSEC is not configured.
An open PR on the draft (#35) adds exactly this language: if a CA performs DNSSEC validation and it fails (expired signatures, broken chain of trust), the CA MUST treat it as a challenge failure and MUST NOT use the record. The rationale is that dns-persist-01 records are long-lived, so a DNSSEC failure has more severe consequences than it would for a transient challenge.
solatic|10 days ago
pepdar|10 days ago