NSE7 Advanced VPN and Zero Trust Practice Question
A FortiGate administrator is configuring OSPF over an IPsec VPN overlay in a hub-and-spoke topology. The spokes have dynamic IPs and use ADVPN. Which THREE conditions are necessary for OSPF to work correctly over the VPN tunnels?
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 OSPF router ID must be unique across all spokes
OSPF requires stable network types and correct interface configuration. For ADVPN, OSPF should use point-to-point network type to avoid DR elections and ensure proper neighbor relationships.
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 OSPF router ID must be unique across all spokes
Why this is correct
OSPF router IDs must be unique to prevent routing issues.
- ✗
The OSPF hello interval must be less than the DPD retry interval
Why it's wrong here
No direct relationship; both can be tuned independently.
- ✗
The hub must have all spoke routes in its routing table before OSPF starts
Why it's wrong here
OSPF will learn routes dynamically; pre-populated routes are not necessary.
- ✓
The tunnel interfaces must have an IP address configured
Why this is correct
OSPF requires an IP address on the interface to form adjacencies.
- ✓
The OSPF network type on the tunnel interfaces must be set to point-to-point
Why this is correct
Point-to-point avoids DR/BDR elections and works well with VPN 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.