NSE7 Advanced VPN and Zero Trust Practice Question
A FortiGate administrator is troubleshooting an IPsec VPN tunnel that fails to establish. The administrator runs 'diagnose vpn ike gateway list' and sees that the IKE gateway is stuck in the 'connecting' state. The administrator confirms that the pre-shared key matches on both peers. Which action should the administrator take next to identify the cause?
⚠ Common exam trap
The trap here is assuming that a matching pre-shared key guarantees phase 1 success; proposal mismatches are a common cause of stuck negotiations.
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
✓
Run 'diagnose debug application ike -1' and check the debug output for proposal mismatches.
When an IKE gateway is stuck in 'connecting', the most likely cause is a phase 1 negotiation failure, such as a proposal mismatch. Enabling IKE debug with 'diagnose debug application ike -1' provides detailed logs that reveal the exact reason for the failure, such as mismatched encryption or DH group. Other commands show status but not the negotiation details needed to pinpoint the issue. Thus, IKE debugging is the correct next step.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Run 'get vpn ipsec tunnel summary' to check the tunnel status.
Why it's wrong here
'get vpn ipsec tunnel summary' provides a summary of IPsec tunnels, including up/down status. If the tunnel is not established, it will show as down, but it does not provide detailed negotiation logs. The administrator already knows the tunnel is not up from the IKE gateway list. To find the cause, deeper IKE debugging is needed. Therefore, this command is not the most useful next step.
- ✗
Run 'diagnose vpn tunnel list' to check the phase 2 selectors.
Why it's wrong here
'diagnose vpn tunnel list' displays the status of established IPsec tunnels, including phase 2 selectors. However, if the tunnel is stuck in phase 1, no phase 2 SAs exist yet, so this command will not show useful information. The issue is at phase 1, so the administrator should focus on IKE debugging rather than tunnel list. Therefore, this action is not the best next step.
- ✓
Run 'diagnose debug application ike -1' and check the debug output for proposal mismatches.
Why this is correct
When an IKE gateway is stuck in 'connecting', it often indicates a phase 1 proposal mismatch or other negotiation failure. Enabling IKE debug with 'diagnose debug application ike -1' provides detailed logs of the negotiation, including proposed and received proposals. This helps identify mismatched encryption, authentication, or DH group settings. Since the pre-shared key is confirmed correct, the next step is to examine the IKE negotiation details. This is the most effective troubleshooting action.
- ✗
Run 'execute vpn ike gateway flush' to clear the IKE gateway and retry.
Why it's wrong here
Flushing the IKE gateway might clear a stuck state, but it does not help identify the root cause. The administrator needs to diagnose why the negotiation is failing. Flushing could temporarily resolve a transient issue, but if the problem is a configuration mismatch, it will persist. Without understanding the cause, the administrator may repeatedly encounter the same problem. Thus, this is not the recommended next step for troubleshooting.
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
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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.