NSE7 Troubleshooting and Diagnostics Practice Question
A FortiGate is configured with an IPsec VPN tunnel to a remote peer. The tunnel is up, but traffic is not passing through it. The administrator runs 'diagnose vpn tunnel list' and sees that the tunnel is established. The administrator then runs 'diagnose debug flow' and sees that traffic is being dropped with the message 'iprope_in_check() check failed, drop'. What is the MOST likely cause of the drop?
⚠ Common exam trap
The trap here is focusing on IPsec configuration when the error clearly points to a firewall policy issue, leading to unnecessary troubleshooting of the tunnel itself.
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
✓
The firewall policy for the VPN traffic is missing or incorrect.
The error 'iprope_in_check() check failed, drop' is generated by the firewall policy check. It means that the packet did not match any allow policy or matched a deny policy. In an IPsec VPN scenario, this often happens when the policy allowing traffic from the VPN tunnel is missing or incorrectly configured. The administrator should verify that a policy exists with the correct incoming interface, source, destination, and service.
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 VPN tunnel is using the wrong pre-shared key.
Why it's wrong here
A wrong pre-shared key would prevent the IPsec tunnel from establishing. The scenario states that the tunnel is up, so the pre-shared key is correct. The drop occurs during traffic processing, not during tunnel negotiation. Therefore, this is not the cause. The issue is with firewall policy matching, not IPsec authentication.
- ✓
The firewall policy for the VPN traffic is missing or incorrect.
Why this is correct
The message 'iprope_in_check() check failed, drop' indicates that the traffic was dropped by the firewall policy check. This typically means that no firewall policy matches the traffic, or the matching policy has an action of deny. In the context of an IPsec VPN, traffic arriving from the tunnel must be matched by a policy that allows it. If the policy is missing or misconfigured, the packet is dropped. This is the most likely cause.
- ✗
The IPsec phase2 selectors do not match the traffic being sent.
Why it's wrong here
If the phase2 selectors did not match, the tunnel would not establish, or traffic would not be encrypted and sent. However, the tunnel is up, and the debug flow shows the packet is being dropped by iprope_in_check, which is a firewall policy check, not an IPsec selector mismatch. A selector mismatch would typically result in a different error, such as 'no matching phase2' or the packet not being routed into the tunnel. Therefore, this is not the cause.
- ✗
The routing table does not have a route to the remote subnet.
Why it's wrong here
If there were no route to the remote subnet, the packet would not be sent to the IPsec tunnel in the first place. The debug flow would show a routing lookup failure, not an iprope_in_check failure. The iprope_in_check failure occurs after routing, when the packet is being checked against firewall policies. Therefore, a missing route is not the cause of this specific drop message.
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.