NSE7 Advanced VPN and Zero Trust Practice Question
A network administrator configured a hub-and-spoke ADVPN with IKEv2. Spoke sites can establish tunnels to the hub, but shortcut tunnels are not being created between spokes. What is the MOST likely cause?
⚠ Common exam trap
A common mix-up: candidates assume shortcut tunnels fail due to authentication or IKE version mismatches, but the core ADVPN mechanism specifically requires auto-discovery to be enabled on the hub to relay spoke-to-spoke information, a detail that is easy to overlook in configuration.
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
✓
Auto-discovery is disabled on the hub FortiGate
In a hub-and-spoke ADVPN with IKEv2, shortcut tunnels between spokes require auto-discovery to be enabled on the hub FortiGate. Auto-discovery allows the hub to exchange IKE information (including NAT-T and IP addresses) between spokes, enabling them to establish direct tunnels. When auto-discovery is disabled on the hub, the hub will not forward the necessary IKE messages (such as the IKE_AUTH exchange with the auto-discovery payload) to other spokes, preventing shortcut tunnel creation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Dead Peer Detection is disabled on the hub
Why it's wrong here
DPD detects peer liveness; disabling it could cause stale tunnels but does not prevent shortcut creation.
- ✓
Auto-discovery is disabled on the hub FortiGate
Why this is correct
Without auto-discovery enabled on the hub, it will not send route advertisements that trigger shortcut tunnel setup between spokes.
- ✗
The spokes are using different IKE versions
Why it's wrong here
All sites must use the same IKE version, but IKEv2 is consistent; this would cause full tunnel failure, not just shortcuts.
- ✗
The IKEv2 authentication method is not set to pre-shared key
Why it's wrong here
IKEv2 supports multiple auth methods; pre-shared key is not required for shortcut tunnels.
Visual reference
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.