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.
A FortiGate administrator receives reports that users cannot access a legitimate website that uses HTTPS. The web filtering profile is configured with strict FortiGuard categories and 'monitor all' for unknown sites. The firewall policy has an SSL/SSH inspection profile set to 'deep-inspection'. What is the most likely cause of the issue?
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 website uses a self-signed certificate which is not trusted by the FortiGate CA bundle
When deep inspection is enabled, the FortiGate decrypts and re-encrypts traffic. If the website's certificate is not trusted by the FortiGate (e.g., self-signed or issuer not in CA bundle), the connection may fail.
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 website uses a self-signed certificate which is not trusted by the FortiGate CA bundle
Why this is correct
Deep inspection requires the FortiGate to trust the server certificate. A self-signed or untrusted CA certificate will cause the connection to fail.
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.
✗
The antivirus profile is blocking a file on the website
Why it's wrong here
Antivirus blocking occurs after decryption; the issue is during the SSL handshake.
✗
The DNS filter is blocking the domain
Why it's wrong here
DNS filter would block at DNS query time, not cause an SSL error.
✗
The website's FortiGuard category is set to 'block'
Why it's wrong here
If the category were blocked, the traffic would be blocked before SSL handshake, not cause a certificate error.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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 website uses a self-signed certificate which is not trusted by the FortiGate CA bundle — When deep inspection is enabled, the FortiGate decrypts and re-encrypts traffic. If the website's certificate is not trusted by the FortiGate (e.g., self-signed or issuer not in CA bundle), the connection may fail.
What should I do if I get this NSE4 question wrong?
Identify which NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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