- A
The remote peer's IP address is unreachable
Why wrong: Unreachability would cause timeout, not proposal rejection.
- B
The phase1 encryption algorithm or integrity algorithm is mismatched
If the local and remote proposals do not have a common algorithm, negotiation fails with 'no acceptable proposal'.
- C
The local FortiGate has the wrong IKE version configured
Why wrong: IKE version mismatch would cause a different error (e.g., 'no acceptable proposal' could appear if one side expects IKEv1 and the other IKEv2, but typically the error is more specific.
- D
The remote peer's pre-shared key is incorrect
Why wrong: A pre-shared key mismatch causes authentication failure after proposal negotiation, not a proposal error.
- E
The Diffie-Hellman group configured is not supported by both peers
DH group is part of the proposal; if mismatched, negotiation fails.
Quick Answer
The answer is a mismatched Diffie-Hellman group or mismatched encryption/integrity algorithms. This error occurs because IKEv2 requires both peers to agree on every parameter in the Phase 1 proposal; if even one setting—such as AES-256 versus AES-128 or DH group 14 versus group 5—differs, the negotiation fails with the “no acceptable proposal” message. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your ability to diagnose Phase 1 failures in site-to-site VPNs, often appearing in troubleshooting scenarios where logs show the error but the configuration looks correct at first glance. A common trap is assuming only encryption matters, when in fact the Diffie-Hellman group is a frequent culprit because it is easy to overlook during peer configuration. Remember the mnemonic “EDD” for Encryption, DH group, and Diffie-Hellman—check all three before blaming the network.
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.
A FortiGate administrator is troubleshooting an IKEv2 VPN tunnel that fails to establish. The remote peer logs show 'no acceptable proposal' error. Which TWO possible causes should the administrator check?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The phase1 encryption algorithm or integrity algorithm is mismatched
The 'no acceptable proposal' error occurs when the two peers cannot agree on a set of parameters. Common causes are mismatched encryption/integrity algorithms (phase1 proposal) or mismatched Diffie-Hellman groups.
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 remote peer's IP address is unreachable
Why it's wrong here
Unreachability would cause timeout, not proposal rejection.
- ✓
The phase1 encryption algorithm or integrity algorithm is mismatched
Why this is correct
If the local and remote proposals do not have a common algorithm, negotiation fails with 'no acceptable proposal'.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The local FortiGate has the wrong IKE version configured
Why it's wrong here
IKE version mismatch would cause a different error (e.g., 'no acceptable proposal' could appear if one side expects IKEv1 and the other IKEv2, but typically the error is more specific.
- ✗
The remote peer's pre-shared key is incorrect
Why it's wrong here
A pre-shared key mismatch causes authentication failure after proposal negotiation, not a proposal error.
- ✓
The Diffie-Hellman group configured is not supported by both peers
Why this is correct
DH group is part of the proposal; if mismatched, negotiation fails.
Related concept
Read the scenario before looking for a memorised answer.
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.
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Advanced VPN and Zero Trust — study guide chapter
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FAQ
Questions learners often ask
What does this NSE7 question test?
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 phase1 encryption algorithm or integrity algorithm is mismatched — The 'no acceptable proposal' error occurs when the two peers cannot agree on a set of parameters. Common causes are mismatched encryption/integrity algorithms (phase1 proposal) or mismatched Diffie-Hellman groups.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 21, 2026
This NSE7 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE7 exam.
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