Final answer:
The protocol that allows a certificate's authenticity to be immediately verified is OCSP (Online Certificate Status Protocol).
Step-by-step explanation:
The protocol that allows a certificate's authenticity to be immediately verified is OCSP (Online Certificate Status Protocol).
OCSP is a real-time protocol used to check the validity and status of a digital certificate. It allows users to verify the authenticity of a certificate by querying the certificate's status directly from the issuing certificate authority.
For example, when a user connects to a website secured with an SSL/TLS certificate, the user's browser can use OCSP to check if the certificate is still valid and hasn't been revoked.
The protocol that allows a certificate's authenticity to be immediately verified is the Online Certificate Status Protocol (OCSP).
OCSP is used as an alternative to the Certificate Revocation List (CRL) and provides the status of an X.509 digital certificate without requiring the client to download the whole list. The protocol is used by various software and browsers to check the revocation status of a digital certificate to ensure it is still valid and has not been revoked.