DNS: Let's Encrypt

https://letsencrypt.org/ru/
- https://github.com/letsencrypt/website
Клиенты
- https://certbot.eff.org/
- https://github.com/Neilpang/acme.sh
  - https://github.com/Neilpang/acme.sh/wiki/dnsapi#89-use-nicru-dns
    - https://github.com/Neilpang/acme.sh/pull/2548
  - https://github.com/Neilpang/acme.sh/wiki/Blogs-and-tutorials

https://it.igro.tech/server-software/letsencrypt-nic-ru-dns-api.html - хорошая статья по использования DNS AIP от ru-center