NSE7 Enterprise Firewall and VDOMs Practice Question
A FortiGate 600E is running multiple VDOMs in NAT mode. The administrator wants to assign a VLAN subinterface to VDOM-A while the parent physical interface remains in the root VDOM. Which configuration step is required to accomplish this?
⚠ Common exam trap
The trap here is assuming that the parent interface must be moved to the target VDOM before creating the subinterface, which is not required and would break other VLANs.
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
✓
Create the VLAN subinterface under the physical interface in the root VDOM, then move the VLAN subinterface to VDOM-A.
VLAN subinterfaces can be individually assigned to different VDOMs while the parent interface remains in the root VDOM. The administrator must create the VLAN under the parent in root, then change the VLAN interface's VDOM assignment. This allows a single physical port to serve multiple VDOMs without moving the parent, preserving root access and other VLANs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a VDOM link between root and VDOM-A and bridge the VLAN traffic across the link.
Why it's wrong here
A VDOM link is a virtual point-to-point connection for inter-VDOM routing, not a way to assign a VLAN subinterface to a different VDOM. Bridging VLAN traffic over a VDOM link adds unnecessary complexity and does not satisfy the requirement of placing the subinterface directly in VDOM-A.
- ✗
Enable VDOM partitioning on the physical interface and assign the VLAN subinterface to VDOM-A.
Why it's wrong here
VDOM partitioning is not a feature on FortiGate; interfaces are assigned to VDOMs individually. The physical interface stays in root, and the VLAN subinterface can be placed in VDOM-A. This option invents a non-existent capability, so it fails the scenario.
- ✗
Assign the physical interface to VDOM-A and create the VLAN subinterface there; the root VDOM will automatically retain management access.
Why it's wrong here
Moving the physical interface to VDOM-A removes it from root, and the root VDOM loses direct access to that port. The scenario requires the parent to stay in root. This would also break any other VLANs on that port belonging to root, so it is incorrect.
- ✓
Create the VLAN subinterface under the physical interface in the root VDOM, then move the VLAN subinterface to VDOM-A.
Why this is correct
On FortiGate, you first create the VLAN subinterface on the parent interface (which is in root), then edit the VLAN interface and change its VDOM to VDOM-A. The parent remains in root. This is the standard method to split VLANs across VDOMs while sharing one physical port.
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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.