CAA Record
A CAA (Certificate Authority Authorization) record is a [[dns|DNS]] record specifying which Certificate Authorities are allowed to issue [[ssl-tls|SSL/TLS certificates]] for a domain. CAA records prevent unauthorized certificate issuance.
Example
A CAA record 'example.com. IN CAA 0 issue "letsencrypt.org"' means only Let's Encrypt can issue certificates for example.com.