NSE7 Advanced VPN and Zero Trust Practice Question
An administrator is troubleshooting an IPsec VPN tunnel that fails to establish. The configuration uses certificates for authentication. The admin sees the following log message: 'Certificate validation failed: unable to get local issuer certificate.' 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
✓
The CA certificate that signed the peer's certificate is not imported on the FortiGate
The error indicates that the FortiGate cannot find the CA certificate that issued the peer's certificate. The CA certificate must be imported and trusted on the FortiGate.
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 peer's certificate has expired
Why it's wrong here
Expired certificate gives a different error (certificate expired).
- ✓
The CA certificate that signed the peer's certificate is not imported on the FortiGate
Why this is correct
The error 'unable to get local issuer certificate' means the issuing CA is missing.
- ✗
The certificate revocation list (CRL) is not configured
Why it's wrong here
CRL is optional; missing CRL does not cause this error.
- ✗
The local certificate does not match the peer's expected CN
Why it's wrong here
CN mismatch causes a different validation error.
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
Courseiva writes every NSE7 question from scratch — 940 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or 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.