[Let’s encrypt / certbot] _acme-challenge が解決できない

ログ

Certbot failed to authenticate some domains (authenticator: manual). The Certificate Authority reported these problems:
  Domain: <ドメイン名>
  Type:   dns
  Detail: DNS problem: NXDOMAIN looking up TXT for _acme-challenge.<ドメイン名> - check that a DNS record exists for this domain

  Domain: <ドメイン名>
  Type:   dns
  Detail: DNS problem: NXDOMAIN looking up TXT for _acme-challenge.<ドメイン名> - check that a DNS record exists for this domain

Hint: The Certificate Authority failed to verify the manually created DNS TXT records. Ensure that you created these in the correct location, or try waiting longer for DNS propagation on the next attempt.

Some challenges have failed.
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /var/log/letsencrypt/letsencrypt.log or re-run Certbot with -v for more details.

対応

certbot に「–debug-challeng」パラメータを追加
「ゆっくり動作させるとうまくいく」らしい・・・それでいいのか Let’s encrypt

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[Let’s encrypt / certbot] 証明書更新に失敗する – Extrose による手記 (stoicsounds.jp)
これの件とかもあったし、Let’s encrypt はどんどん不安定になるな・・・
無償だからやむなしか、とはいえ 証明書更新毎にトラブルシューティングは面倒だ