NSE7 Advanced VPN and Zero Trust Practice Question
A FortiGate has an IPsec VPN with a remote peer that uses IKEv2. The administrator wants to ensure that child SA rekeying uses PFS (Perfect Forward Secrecy) with Diffie-Hellman group 14. Which CLI command should the administrator configure on the FortiGate's phase 2 proposal?
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; set dhgrp 14
To enable PFS with DH group 14 on the phase 2 proposal, the correct CLI command is 'set pfs enable' and 'set dhgrp 14'. The command 'set proposal aes256-sha256' defines encryption/integrity, not PFS. The other options do not set PFS correctly.
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 auto-negotiate enable; set dh-group 14
Why it's wrong here
Auto-negotiate is not related to PFS.
- ✓
set pfs enable; set dhgrp 14
Why this is correct
This correctly enables PFS and sets the Diffie-Hellman group to 14.
- ✗
set proposal aes256-sha256 dh-group 14
Why it's wrong here
The dh-group parameter is not part of the proposal string; it is a separate command.
- ✗
set pfs enable; set dh-group 14
Why it's wrong here
The correct CLI parameter is 'dhgrp', not 'dh-group'.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.