NSE7 Enterprise Firewall and VDOMs Practice Question
An administrator deploys a FortiGate in transparent mode with two VDOMs: one for the internal network and one for DMZ. The admin notices that ARP requests from internal hosts are not reaching the DMZ servers even though they are on the same VLAN. What is the most likely cause?
⚠ Common exam trap
Candidates often assume transparent mode operates as a simple bridge that forwards all Layer 2 traffic between all interfaces, forgetting that VDOMs create strict Layer 2 isolation boundaries even in transparent mode.
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
✓
VDOMs in transparent mode are isolated layer 2 domains; inter-VDOM routing is required for communication
In transparent mode, each VDOM acts as an independent Layer 2 forwarding domain with its own MAC address table and VLAN database. ARP requests are broadcast frames that are confined to the VDOM where they originate; they are not forwarded to other VDOMs. Therefore, even if the internal and DMZ interfaces are on the same VLAN, the ARP request from an internal host will never reach a DMZ server unless inter-VDOM routing (Layer 3 forwarding between VDOMs) is explicitly configured.
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 FortiGate is not configured to proxy ARP
Why it's wrong here
Proxy ARP is not needed; the issue is VDOM isolation.
- ✓
VDOMs in transparent mode are isolated layer 2 domains; inter-VDOM routing is required for communication
Why this is correct
Correct. VDOMs separate broadcast domains.
- ✗
The internal and DMZ VDOMs are in different VLANs on the same physical interface
Why it's wrong here
Even on same VLAN, VDOMs isolate layer 2.
- ✗
Transparent mode does not support VDOMs
Why it's wrong here
Transparent mode does support VDOMs.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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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.