acme-dns: DNS-01 without handing over the key to the whole zone (CNAME delegation of _acme-challenge) with certbot and cert-manager

NS auth.example.com → acme-dns; POST /register → username, password, fulldomain; CNAME _acme-challenge.example.com → . certbot certonly –manual –manual-auth-hook /etc/letsencrypt/acme-dns-auth.py –preferred-challenges dns -d ‘*.example.com’ -d example.com. On Kubernetes, the dns01.acmeDNS solver with accountSecretRef. acme-dns 2.0.2 (February 2025) is still active.

September 26, 2026 · 4 min

2048-bit DKIM: the key does not fit in a 255-character TXT

The 255 limit is per string, not per record. fold -w 255 + quotes, all in the same TXT; the verifier concatenates them. Route 53 and Cloud DNS require it; Cloudflare does it for you.

September 25, 2026 · 4 min