What is used to validate a digital certificate?

Anjali D.Apr 24, 2026

The correct answer is B, CRL. A Certificate Revocation List is the mechanism a Certificate Authority publishes to let relying parties check whether a certificate has been revoked before its expiration date, which is exactly what validation requires. When your browser or VPN client receives a certificate, it checks the CRL (or uses OCSP, which serves the same purpose) to confirm the cert is still trusted and has not been compromised or withdrawn. The other options are all PKI-adjacent but serve different roles, IPsec is a tunneling protocol, S/MIME handles email encryption and signing, and PKCS is a family of cryptographic standards for things like key storage and certificate syntax, none of them are the revocation/validation mechanism being asked about here. Anyone in the group who got tripped up by PKCS, I get it, it sounds like it should be the "certificate standard" answer, but the question is specifically about validation, not format or structure. Would love to hear if others interpreted this differently.

Luis F.Mar 31, 2026

Went with B, CRL, because revocation lists are literally what validates certs, passed first try.

Mei-Ling H.Apr 18, 2026

CRL, Certificate Revocation List, is exactly right here. The CA publishes the CRL so any relying party can check whether a certificate has been revoked before trusting it, which is the core step in validating that a certificate is still good.

Lena V.Apr 10, 2026

Took the 156-215.77 back in March and this exact concept showed up, just worded a little differently, something like "what mechanism is used to check the revocation status of a certificate." CRL, Certificate Revocation List, is the list published by a CA that contains all certificates it has revoked before their expiration date, and when a system needs to validate a cert, it checks that list to confirm the cert has not been pulled. IPsec is a tunneling and encryption protocol suite, S/MIME handles email encryption and signing, and PKCS is a group of public key cryptography standards, none of those are the validation mechanism itself. I almost second-guessed myself toward PKCS because it sounds related to PKI infrastructure, but the question is specifically about the revocation check process, and that is CRL, answer B, full stop.

Eitan E.Apr 5, 2026

The CRL, or Certificate Revocation List, is what a relying party checks to confirm that a certificate has not been revoked before trusting it, and this is a core PKI concept that shows up in the Check Point firewall certificate validation flow. Quick question for you though: do you understand the difference between checking a CRL and using OCSP for the same purpose, because the exam occasionally tests whether you know when a gateway might prefer one over the other?