NSE7 Advanced VPN and Zero Trust Practice Question
A network administrator is troubleshooting an IPsec VPN tunnel between two FortiGates. The tunnel is established but traffic is not passing. The administrator runs 'diagnose vpn ike log' and sees 'no matching policy for this IPsec SA'. What is the most likely cause?
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
✓
There is no firewall policy allowing traffic from the local network to the remote network via the VPN tunnel interface
The error indicates that the IKE SA exists but no firewall policy matches the traffic to use the tunnel. The tunnel interface is likely configured but the policy to allow traffic through the tunnel is missing or incorrect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The phase2 selectors do not match between peers
Why it's wrong here
Phase2 mismatch would cause the IPsec SA to fail; the error mentions IPsec SA exists.
- ✓
There is no firewall policy allowing traffic from the local network to the remote network via the VPN tunnel interface
Why this is correct
Even if the tunnel is up, a firewall policy must explicitly permit traffic to use the tunnel. Without it, traffic is dropped.
- ✗
The pre-shared key is mismatched
Why it's wrong here
A mismatched PSK would prevent the IKE SA from being established, not cause a policy mismatch.
- ✗
The tunnel interface is administratively down
Why it's wrong here
If the tunnel interface is down, the IPsec SA would not be established.
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
This NSE7 question is part of Courseiva's 940-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.