Certbot cannot use CNAME-delegated DNS-01 challenges
Certbot cannot issue certificates through a CNAME-delegated _acme-challenge name, so servers that cannot use port 80 have no easy DNS-01 path.
Tier II · Emerging Problems that are still building up.
3 public reports · first reported 27 August 2026 · last reported 28 August 2026
What's going wrong
Operators who want Let's Encrypt certificates without opening port 80 often turn to DNS-01 validation, and many set up a static CNAME that points _acme-challenge records into a separate delegated zone.
AI-assisted: written with the help of AI from the reports. The idea report has the full summary.
In the idea report
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