Over a hundred certificate authorities (CAs) have the power to issue certificates which vouch for the identity of your website. Certificate Authority Authorization (CAA) is a way for you to whitelist the CAs you actually use so you can minimize your risk from security vulnerabilities in all the others.
Beginning September 8, 2017, all certificate authorities will be required to respect your CAA policy, so now is the perfect time to set up CAA. Setting up CAA using this tool is an easy way to improve your website's security. Learn More