DNS provider
No API key required.
After you click Request certificate, the next page will
show the TXT records to add at your registrar. Once they're in
place, click Complete to finish issuance.
Existing private key (optional)
Leave blank to have certbot generate a fresh 4096-bit RSA key.
Provide a key here to keep an existing one (renewals, key continuity, pre-generated keys).
Either upload the file or paste its contents — the file takes precedence if both are given.