The answer is that the VDOM link is operating in transparent mode, which allows inter-VDOM traffic to be bridged at Layer 2 without requiring a routing policy. In transparent mode, the VDOM link forwards frames based on MAC addresses rather than IP addresses, so if both VDOMs share the same VLAN ID and IP subnet, traffic simply passes through the link as if it were a switch, bypassing the Layer 3 routing policies that would normally govern inter-VDOM traffic. On the Fortinet NSE 7 Advanced Security exam, this scenario tests your understanding of how VDOM links interact with the firewall’s forwarding plane—specifically, that transparent mode creates a Layer 2 bridge, not a Layer 3 route. A common trap is assuming all inter-VDOM traffic requires an explicit policy; in reality, transparent mode implicitly allows bridging within the same subnet. Memory tip: think “transparent = bridge, not route”—if the VLAN and subnet match, the traffic slips through without a policy.
NSE7 Enterprise Firewall and VDOMs Practice Question
This NSE7 practice question tests your understanding of enterprise firewall and vdoms. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
During a security audit, it is found that traffic between two VDOMs is allowed even though no inter-VDOM routing policy is configured. The VDOMs are connected via a VDOM link. What could explain this behavior?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The VDOM link is operating in transparent mode
If the VDOM link is configured with the same VLAN ID and IP subnet, traffic may be bridged at Layer 2, bypassing Layer 3 policies. Alternatively, a policy might be implicitly allowing traffic.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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 in NAT mode
Why it's wrong here
NAT mode does not bypass inter-VDOM routing policies.
✗
The VDOMs are in the same administrative domain
Why it's wrong here
Administrative domain is a FortiManager concept, not affecting traffic.
✗
The VDOM link is using the same interface IP
Why it's wrong here
Same IP would cause conflict, not allow traffic.
✓
The VDOM link is operating in transparent mode
Why this is correct
If the VDOM link is in transparent mode, it bridges traffic without routing, so inter-VDOM routing policies are not required.
Related concept
Access ports place end devices into a single VLAN.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related NSE7 questions on switching, trunking, and access-port configuration.
Enterprise Firewall and VDOMs — This question tests Enterprise Firewall and VDOMs — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The VDOM link is operating in transparent mode — If the VDOM link is configured with the same VLAN ID and IP subnet, traffic may be bridged at Layer 2, bypassing Layer 3 policies. Alternatively, a policy might be implicitly allowing traffic.
What should I do if I get this NSE7 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related NSE7 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Question Discussion
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