The answer is that the CA certificate that signed the peer's certificate is not imported on the FortiGate. This is the most likely cause because the log message "unable to get local issuer certificate" specifically indicates that during the IPsec VPN certificate validation process, the FortiGate cannot locate a trusted root certificate authority (CA) certificate in its local store to verify the chain of trust for the peer's certificate. On the Fortinet NSE 7 Advanced Security NSE7 exam, this scenario tests your understanding of PKI trust models within IPsec authentication, often appearing as a trap where candidates mistakenly blame the peer’s certificate expiry or a mismatched IKE version. A common memory tip: if the error says "local issuer," think "local CA missing"—the FortiGate needs the issuing CA certificate imported and marked as trusted under System > Certificates before it can validate any peer certificate signed by that authority.
NSE7 Advanced VPN and Zero Trust Practice Question
This NSE7 practice question tests your understanding of advanced vpn and zero trust. 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.
An administrator is troubleshooting an IPsec VPN tunnel that fails to establish. The configuration uses certificates for authentication. The admin sees the following log message: 'Certificate validation failed: unable to get local issuer certificate.' 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 certificate that signed the peer's certificate is not imported on the FortiGate
The error indicates that the FortiGate cannot find the CA certificate that issued the peer's certificate. The CA certificate must be imported and trusted on the FortiGate.
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 peer's certificate has expired
Why it's wrong here
Expired certificate gives a different error (certificate expired).
✓
The CA certificate that signed the peer's certificate is not imported on the FortiGate
Why this is correct
The error 'unable to get local issuer certificate' means the issuing CA is missing.
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 certificate revocation list (CRL) is not configured
Why it's wrong here
CRL is optional; missing CRL does not cause this error.
✗
The local certificate does not match the peer's expected CN
Why it's wrong here
CN mismatch causes a different validation 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 NSE7 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 NSE7 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.
Advanced VPN and Zero Trust — This question tests Advanced VPN and Zero Trust — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The CA certificate that signed the peer's certificate is not imported on the FortiGate — The error indicates that the FortiGate cannot find the CA certificate that issued the peer's certificate. The CA certificate must be imported and trusted on the FortiGate.
What should I do if I get this NSE7 question wrong?
Identify which NSE7 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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