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
This is not a valid FortiOS command.
- ✓
diagnose debug application ike -1
Why this is correct
This enables IKE debug with level -1 for verbose output.
- ✗
get vpn ipsec tunnel details
Why it's wrong here
This shows tunnel status but not real-time negotiation details.
- ✗
diagnose debug application ipsec -1
Why it's wrong here
This command is not standard; correct is 'diagnose debug application ike'.
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.