The correct answer is that the CA which issued the SSL VPN certificate is not trusted by the client. This is the most likely cause because the debug output reveals an SSL/TLS handshake failure, which specifically indicates a certificate trust issue rather than an expiration or authentication problem; when a FortiGate presents a certificate signed by a Certificate Authority that the client’s operating system or browser does not have in its trusted root store, the client rejects the connection outright. On the Fortinet NSE 4 Network Security Professional exam, this scenario tests your ability to distinguish between certificate trust errors and other common SSL VPN failures, such as expired certificates or mismatched common names—a frequent trap is assuming the certificate is expired when the real issue is a missing root CA. Remember the memory tip: “Trust the chain, not just the date”—if the client doesn’t trust the issuing CA, no amount of valid dates will fix the handshake.
NSE4 Security Profiles Practice Question
This NSE4 practice question tests your understanding of security profiles. 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.
Exhibit
Refer to the exhibit.
diagnose debug application sslvpn -1
debug sslvpn error: SSL_accept failed: error:14094418:SSL routines:ssl3_read_bytes:tlsv1 alert unknown ca
debug sslvpn error: SSL_accept failed: error:14094418:SSL routines:ssl3_read_bytes:tlsv1 alert unknown ca
Refer to the exhibit. A FortiGate SSL VPN user is unable to connect. The debug output shows the above error. 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 CA that issued the SSL VPN certificate is not trusted by the client.
The debug output indicates an SSL/TLS handshake failure, specifically that the client does not trust the server's certificate. This occurs when the Certificate Authority (CA) that issued the SSL VPN certificate is not in the client's trusted root store. Option B correctly identifies this as the most likely cause because the error is a certificate trust issue, not an expiration or authentication problem.
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 SSL VPN certificate has expired.
Why it's wrong here
Expired certificate shows different error.
✓
The CA that issued the SSL VPN certificate is not trusted by the client.
Why this is correct
Unknown CA error indicates trust issue.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse certificate trust issues (CA not trusted) with certificate expiration, but the debug output clearly shows a trust chain failure, not a validity date error.
Trap categories for this question
Command / output trap
Expired certificate shows different error.
Detailed technical explanation
How to think about this question
During SSLVPN establishment, the FortiGate presents its certificate to the client. The client verifies the certificate chain up to a trusted root CA. If the issuing CA is not in the client's trust store, the handshake fails with an 'unknown CA' or 'certificate not trusted' error. This is distinct from certificate expiration (checked via the validity dates) or revocation (checked via CRL/OCSP). In real-world scenarios, this often happens when using a self-signed certificate or an internal CA that hasn't been imported into client devices.
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 practitioner preparing for the NSE4 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Profiles — This question tests Security Profiles — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The CA that issued the SSL VPN certificate is not trusted by the client. — The debug output indicates an SSL/TLS handshake failure, specifically that the client does not trust the server's certificate. This occurs when the Certificate Authority (CA) that issued the SSL VPN certificate is not in the client's trusted root store. Option B correctly identifies this as the most likely cause because the error is a certificate trust issue, not an expiration or authentication problem.
What should I do if I get this NSE4 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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