NSE7 Troubleshooting and Diagnostics Practice Question
When troubleshooting an IPsec VPN phase 1 negotiation failure, which debug command should the administrator run to see detailed IKE negotiation messages?
⚠ Common exam trap
Watch out — candidates often confuse the IKE debug command with the IPsec debug command, mistakenly thinking 'diagnose debug application ipsec -1' will show Phase 1 negotiation details, when in fact it only shows kernel-level IPsec processing and not the IKE control-plane messages.
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
✓
diagnose debug application ike -1
The command 'diagnose debug application ike -1' enables detailed IKE (Internet Key Exchange) debug messages in FortiOS, which are essential for troubleshooting Phase 1 negotiation failures. This command captures the full IKE negotiation exchange, including proposals, authentication, and Diffie-Hellman group selection, allowing the administrator to identify where the failure occurs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
diagnose vpn ike log
Why it's wrong here
The diagnose vpn ike log command filters IKE daemon output by tunnel or peer, which is narrower than the full negotiation trace required here. It is tempting because it targets IKE specifically, but it would be the correct choice when you already know which gateway and need to isolate its messages rather than capture all phase 1 exchanges.
- ✓
diagnose debug application ike -1
Why this is correct
`diagnose debug application ike -1` enables verbose IKE daemon logging, exposing phase 1 proposal exchanges, transform mismatches and vendor ID payloads. The `-1` level prints every negotiation message, satisfying the stem's demand for detailed IKE troubleshooting output rather than summary status or filtered event logs.
- ✗
get vpn ipsec tunnel details
Why it's wrong here
The get vpn ipsec tunnel details command displays current tunnel status, selectors and counters, not the live IKE packet exchange. It is tempting because it reports phase 1 and phase 2 state, but it would be the right choice for confirming whether a tunnel is up or down, not for observing the negotiation messages themselves.
- ✗
diagnose debug application ipsec -1
Why it's wrong here
The diagnose debug application ipsec -1 command enables verbose IPsec debug output, but it does not restrict capture to IKE negotiation messages specifically. It is tempting because it produces detailed IPsec diagnostics, yet it would be the correct choice when troubleshooting data-plane or kernel-level IPsec issues rather than phase 1 IKE exchanges.
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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JA
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.