Chris wants to check to see if a certificate has been revoked. What protocol can he use to validate the current status of a certificate?

The Online Certificate Status Protocol (OCSP) is used to validate certificate status, including checking to see if the certificate is on a certificate revocation list (CRL). TLS is Transport Layer Security, a protocol used to encrypt data in transit between systems that relies on cryptographic certificates, but it is not used to validate the status of certificates on a CRL. Despite SSL itself being outmoded, the term SSL is commonly used to refer to TLS—but here, neither TLS nor SSL is the right option. OCRS was made up for this question.