This NSE4 practice question tests your understanding of authentication and vpn. 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 configuring IPsec VPN between two sites. The Phase 1 negotiation fails with the error 'no proposal chosen'. Which two settings must match on both VPN peers?
Why wrong: Pre-shared key must match, but local ID can be different (it's used for identification). The error 'no proposal chosen' is about algorithms, not PSK.
B
Dead peer detection interval and retry count
Why wrong: DPD settings do not affect proposal negotiation.
C
Remote gateway IP and Phase 2 selectors
Why wrong: Remote gateway IP must be correct, but Phase 2 selectors are for Phase 2, not Phase 1 negotiation.
D
Encryption algorithm and authentication algorithm
Correct. The proposal includes encryption, authentication, and DH group. Mismatch causes 'no proposal chosen'.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Encryption algorithm and authentication algorithm
The proposal (encryption and authentication algorithms) and the Diffie-Hellman group must match between peers for Phase 1 to succeed. These are the key parameters negotiated during Phase 1.
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.
✗
Pre-shared key and local ID
Why it's wrong here
Pre-shared key must match, but local ID can be different (it's used for identification). The error 'no proposal chosen' is about algorithms, not PSK.
✗
Dead peer detection interval and retry count
Why it's wrong here
DPD settings do not affect proposal negotiation.
✗
Remote gateway IP and Phase 2 selectors
Why it's wrong here
Remote gateway IP must be correct, but Phase 2 selectors are for Phase 2, not Phase 1 negotiation.
✓
Encryption algorithm and authentication algorithm
Why this is correct
Correct. The proposal includes encryption, authentication, and DH group. Mismatch causes 'no proposal chosen'.
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 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.
Authentication and VPN — This question tests Authentication and VPN — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Encryption algorithm and authentication algorithm — The proposal (encryption and authentication algorithms) and the Diffie-Hellman group must match between peers for Phase 1 to succeed. These are the key parameters negotiated during Phase 1.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This NSE4 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 NSE4 exam.
Question Discussion
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