NSE7 Advanced VPN and Zero Trust Practice Question
A FortiGate administrator is configuring an IPsec VPN with IKEv2 and wants to ensure that the tunnel uses perfect forward secrecy (PFS). Which phase2 configuration is required?
⚠ Common exam trap
Many exam-takers confuse the phase1 dh-group setting with phase2 PFS, or placing the 'pfs enable' command in the wrong phase.
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
✓
Set 'pfs enable' in phase2 proposal.
Perfect forward secrecy in IPsec is enabled in the phase2 proposal by setting 'pfs enable'. This forces a new Diffie-Hellman exchange for each phase2 rekey, ensuring that compromised keys do not compromise past or future sessions. The phase1 dh-group setting is separate and does not enable PFS for phase2.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set 'pfs enable' in phase2 proposal.
Why this is correct
In FortiOS, PFS is enabled in the phase2 proposal by setting 'pfs enable'. This ensures that a new Diffie-Hellman exchange occurs for each phase2 rekey, providing perfect forward secrecy. Without this, the tunnel would not use PFS, and the requirement would not be met. This command is specific to phase2 and is the correct way to enable PFS.
- ✗
Set 'pfs enable' in phase1 proposal.
Why it's wrong here
The 'pfs' setting is not valid in phase1 proposals. PFS is a phase2 concept that determines whether a new DH exchange occurs during phase2 rekey. Configuring it in phase1 would result in an error or be ignored. The correct place to enable PFS is in the phase2 proposal, making this option incorrect.
- ✗
Set 'pfs disable' in phase2 proposal.
Why it's wrong here
Setting 'pfs disable' explicitly turns off perfect forward secrecy. This would not meet the requirement to use PFS. In fact, it would do the opposite. The administrator must ensure PFS is enabled, not disabled, to achieve the desired security. This option is incorrect for the scenario.
- ✗
Set 'dh-group 14' in phase1 proposal.
Why it's wrong here
The 'dh-group' setting in phase1 defines the Diffie-Hellman group used for the initial IKE SA key exchange. While it is related to PFS, it does not enable PFS for phase2. PFS for phase2 is controlled by the 'pfs' setting in phase2. Setting dh-group in phase1 alone does not guarantee PFS for phase2, so this option is not sufficient.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
Related to this question
About these practice questions
Courseiva writes every NSE7 question from scratch — 718 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Fortinet exam blueprint
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.