The answer is to enable Dead Peer Detection (DPD) on the tunnel interface and increase the phase2 rekey time to 8 hours. DPD ensures the FortiGate actively verifies the peer’s availability, quickly detecting and recovering from path failures that cause intermittent packet loss, while a longer rekey interval reduces the frequency of key regeneration events that can momentarily disrupt traffic. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding of IPsec VPN stability mechanisms under IKEv2, often trapping candidates who focus on encryption settings rather than session maintenance. A common memory tip is “DPD for dead, rekey for delay”—DPD handles peer liveliness, and extending the rekey timer minimizes the brief loss during key refresh cycles.
NSE7 Advanced VPN and Zero Trust Practice Question
This NSE7 practice question tests your understanding of advanced vpn and zero trust. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company has two FortiGate devices at different sites connected via an IPsec VPN tunnel using IKEv2. The tunnel is established but intermittent packet loss is observed. Which two configuration changes should be applied to improve stability? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the phase2 rekey time to 8 hours.
Increasing the phase2 rekey time to 8 hours (Option D) reduces the frequency of rekey events, which can cause brief packet loss during key regeneration. This is especially beneficial for stability when the tunnel experiences intermittent loss due to rekey timing. A longer rekey interval minimizes disruptions, making it a correct choice.
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.
✗
Reduce the DPD retry interval to 3 seconds.
Why it's wrong here
Too aggressive; may cause false timeouts and unnecessary rekeying.
✗
Increase the phase1 lifetime to 86400 seconds.
Why it's wrong here
Phase1 rekey is less frequent; changing it does not address the intermittent packet loss typically caused by phase2 rekey.
✗
Change the IKE version to IKEv1.
Why it's wrong here
IKEv2 is generally more stable than IKEv1 for IPsec VPNs.
✓
Increase the phase2 rekey time to 8 hours.
Why this is correct
Longer rekey intervals reduce the frequency of rekeying, which can disrupt traffic.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable Dead Peer Detection (DPD) on the tunnel interface.
Why this is correct
DPD detects peer unreachability and triggers re-establishment, improving stability.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think reducing DPD intervals or increasing lifetimes always improves stability, but in reality, aggressive DPD can cause flapping on lossy links, and IKEv2 is inherently more stable than IKEv1 for VPN tunnels.
Detailed technical explanation
How to think about this question
IKEv2 uses a single exchange for both phase1 and phase2, and DPD is natively supported via INFORMATIONAL exchanges (RFC 7296). Intermittent packet loss during rekey occurs because the IPsec SA is temporarily torn down and rebuilt; extending the phase2 rekey time reduces this event frequency. Enabling DPD on the tunnel interface (Option E) ensures the FortiGate actively monitors peer liveness using RFC-compliant keepalives, allowing faster detection of path failures and recovery without waiting for upper-layer timeouts.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Increase the phase2 rekey time to 8 hours. — Increasing the phase2 rekey time to 8 hours (Option D) reduces the frequency of rekey events, which can cause brief packet loss during key regeneration. This is especially beneficial for stability when the tunnel experiences intermittent loss due to rekey timing. A longer rekey interval minimizes disruptions, making it a correct choice.
What should I do if I get this NSE7 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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