The answer is that the 'untrusted-caname' must be set to a trusted CA certificate, not to 'Fortinet_CA_SSL'. When the SSL/SSH profile uses an untrusted CA like Fortinet_CA_SSL to re-sign certificates from untrusted servers, the client browser does not recognize that CA as valid, causing HTTPS websites to fail with certificate warnings or connection errors. This occurs because deep inspection requires the FortiGate to re-sign the server’s certificate with a CA that the client already trusts; if the re-signing CA is itself untrusted, the chain breaks. On the Fortinet NSE 4 Network Security Professional exam, this concept tests your understanding of how SSL/SSH inspection profiles handle untrusted server certificates and the critical distinction between trusted and untrusted CAs. A common trap is assuming any CA will work for re-signing, but the client must have the re-signing CA in its trust store. Memory tip: "Untrusted CA re-signs untrusted server? Double untrusted equals double failure."
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.
```
config firewall ssl-ssh-profile
edit "deep-inspection"
set caname "Fortinet_CA_SSL"
config https
set ports 443
set status deep-inspection
end
set untrusted-caname ""
set whitelist-mode disable
next
end
```
Refer to the exhibit. An administrator has configured the SSL/SSH profile shown. However, users are unable to access HTTPS websites. 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.
Refer to the exhibit.
```
config firewall ssl-ssh-profile
edit "deep-inspection"
set caname "Fortinet_CA_SSL"
config https
set ports 443
set status deep-inspection
end
set untrusted-caname ""
set whitelist-mode disable
next
end
```
A
The 'untrusted-caname' should be set to a trusted CA certificate to handle untrusted server certificates.
Without a trusted CA for untrusted certificates, clients will see certificate warnings.
B
The port is set to 443, but HTTPS also uses port 8443.
Why wrong: Port 443 is the standard; other ports can be added if needed.
C
The 'caname' is set to 'Fortinet_CA_SSL', which is not a valid certificate name.
Why wrong: This is a valid name for the FortiGate's CA certificate.
D
The 'whitelist-mode' is disabled, which prevents inspection.
Why wrong: Whitelist mode is for excluding domains; disabling it is normal.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'untrusted-caname' should be set to a trusted CA certificate to handle untrusted server certificates.
Option A is correct because when the SSL/SSH profile has 'untrusted-caname' set to 'Fortinet_CA_SSL' (an untrusted CA), the FortiGate cannot re-sign certificates from untrusted servers with a trusted CA. This causes HTTPS websites to fail as the client receives an untrusted certificate warning or connection error. Setting 'untrusted-caname' to a trusted CA certificate ensures that even untrusted server certificates are re-signed with a certificate the client trusts.
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 'untrusted-caname' should be set to a trusted CA certificate to handle untrusted server certificates.
Why this is correct
Without a trusted CA for untrusted certificates, clients will see certificate warnings.
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 port is set to 443, but HTTPS also uses port 8443.
Why it's wrong here
Port 443 is the standard; other ports can be added if needed.
✗
The 'caname' is set to 'Fortinet_CA_SSL', which is not a valid certificate name.
Why it's wrong here
This is a valid name for the FortiGate's CA certificate.
✗
The 'whitelist-mode' is disabled, which prevents inspection.
Why it's wrong here
Whitelist mode is for excluding domains; disabling it is normal.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the 'caname' and 'untrusted-caname' fields, assuming any CA name is sufficient, without understanding that the CA must be trusted by the client for the re-signed certificate to be accepted.
Detailed technical explanation
How to think about this question
In SSL inspection, the FortiGate acts as a man-in-the-middle, decrypting traffic and re-encrypting it with a CA certificate. The 'caname' is used to re-sign certificates for trusted servers, while 'untrusted-caname' is used for servers with untrusted certificates. If 'untrusted-caname' points to an untrusted CA, the client will reject the re-signed certificate, breaking HTTPS access. This is a common misconfiguration when deploying deep inspection without importing a trusted root CA to clients.
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 'untrusted-caname' should be set to a trusted CA certificate to handle untrusted server certificates. — Option A is correct because when the SSL/SSH profile has 'untrusted-caname' set to 'Fortinet_CA_SSL' (an untrusted CA), the FortiGate cannot re-sign certificates from untrusted servers with a trusted CA. This causes HTTPS websites to fail as the client receives an untrusted certificate warning or connection error. Setting 'untrusted-caname' to a trusted CA certificate ensures that even untrusted server certificates are re-signed with a certificate the client trusts.
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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