The answer is that the user's certificate has been revoked. When a smart card is used for authentication, the PIN only unlocks the private key stored on the card; the actual identity verification depends on the validity of the user’s certificate within a trusted certificate chain. Even with the correct PIN and a non-expired card, if the certificate has been revoked—due to compromise, termination, or policy change—the system will fail the authentication during a Certificate Revocation List (CRL) or Online Certificate Status Protocol (OCSP) check. On the CISSP exam, this scenario tests your understanding of the Public Key Infrastructure (PKI) lifecycle, specifically that revocation is separate from expiration and that smart card authentication relies on certificate status, not just the card’s physical validity. A common trap is assuming the PIN or card expiration is the issue, but the key is that revocation invalidates the certificate regardless. Memory tip: “PIN unlocks the key, but revocation blocks the trust.”
CISSP Identity and Access Management Practice Question
This CISSP practice question tests your understanding of identity and access management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses smart cards for authentication to workstations. A user inserts their smart card but is prompted for a PIN. The user enters the correct PIN but authentication fails. The smart card is not expired. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The user's certificate is revoked
When a smart card is used for authentication, the PIN unlocks the private key stored on the card, but the actual authentication typically relies on a certificate chain and the validity of the user's certificate. If the certificate has been revoked (e.g., due to compromise or termination), the Certificate Revocation List (CRL) or Online Certificate Status Protocol (OCSP) check will fail, causing authentication to be denied even though the PIN is correct and the card is not expired.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The PIN is incorrectly stored on the card
Why it's wrong here
PIN is verified by the card; if correct, it would succeed.
✗
The smart card driver is outdated
Why it's wrong here
Driver issues might cause unrecognized card, not PIN failure.
✗
The workstation's clock is off by more than 5 minutes
Why it's wrong here
Clock skew affects Kerberos tickets, not smart card PIN verification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume PIN entry failure is the only smart card authentication issue, but the PIN only unlocks the private key; the certificate's revocation status is a separate, often overlooked, layer that can cause authentication to fail after correct PIN entry.
Detailed technical explanation
How to think about this question
Smart card authentication in a PKI environment uses the X.509 certificate stored on the card; the relying party (workstation) performs a revocation check by downloading a CRL or querying an OCSP responder (RFC 6960). If the certificate's serial number appears on the CRL or the OCSP response indicates 'revoked', authentication is denied regardless of PIN correctness. In real-world scenarios, revocation is often triggered by employee termination or device loss, and the CRL distribution point (CDP) must be reachable for the check to succeed.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Identity and Access Management — This question tests Identity and Access Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The user's certificate is revoked — When a smart card is used for authentication, the PIN unlocks the private key stored on the card, but the actual authentication typically relies on a certificate chain and the validity of the user's certificate. If the certificate has been revoked (e.g., due to compromise or termination), the Certificate Revocation List (CRL) or Online Certificate Status Protocol (OCSP) check will fail, causing authentication to be denied even though the PIN is correct and the card is not expired.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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