Let's Encrypt

DNS validation allows for certificate issuance requests to be verified using DNS records, rather than by serving content over HTTP. The acme-dns-certbot tool is used to connect Certbot to a third-party DNS server where the certificate validation records can be set automatically via an API when you request a certificate. The advantage of this is that you don’t need to integrate Certbot directly with your DNS provider , nor do you need to grant it unrestricted access to your full DNS configuration