This PCNSE practice question tests your understanding of core concepts and architecture. 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.
A company needs to deploy a firewall in transparent inline mode to filter traffic between two switches without requiring any IP address changes on existing devices. Which interface type should be configured?
Virtual Wire
Virtual Wire bridges two ports without IP, providing transparent inline inspection.
Tap
Why wrong: Tap interface is for monitoring only, not inline filtering.
Layer3
Why wrong: Layer3 interfaces require IP configuration and are not transparent.
Layer2
Why wrong: Layer2 can be transparent but requires a management IP and is less efficient than Virtual Wire.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Virtual Wire
Virtual Wire (VWire) is the correct interface type because it allows the firewall to operate in transparent inline mode without requiring any IP address changes on existing devices. In VWire mode, the firewall acts as a Layer 2 bump in the wire, forwarding traffic between two interfaces based on MAC addresses without participating in routing or requiring IP configuration on the firewall interfaces themselves.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Virtual Wire
Why this is correct
Virtual Wire bridges two ports without IP, providing transparent inline inspection.
Related concept
Read the scenario before looking for a memorised answer.
Tap
Why it's wrong here
Tap interface is for monitoring only, not inline filtering.
Layer3
Why it's wrong here
Layer3 interfaces require IP configuration and are not transparent.
Layer2
Why it's wrong here
Layer2 can be transparent but requires a management IP and is less efficient than Virtual Wire.
Common exam traps
The trap here is that candidates confuse Layer2 interfaces with Virtual Wire, assuming any transparent mode works the same, but Layer2 interfaces require bridge groups or VLAN configuration and do not provide the same zero-touch inline deployment as Virtual Wire.
Detailed technical explanation
Virtual Wire interfaces pair two firewall ports into a logical wire, forwarding frames based on MAC learning and a simple forwarding table, with no spanning tree or routing involvement. A subtle behavior is that VWire supports jumbo frames and can enforce security policies on non-IP protocols (e.g., MPLS, PPPoE) because it operates at Layer 2, making it ideal for transparent inspection in environments where IP renumbering is impossible. In real-world scenarios, VWire is often used to insert a firewall into an existing data center leaf-spine fabric without disrupting the Layer 2 topology.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Core Concepts and Architecture — This question tests Core Concepts and Architecture — Read the scenario before looking for a memorised answer..
The correct answer is: Virtual Wire — Virtual Wire (VWire) is the correct interface type because it allows the firewall to operate in transparent inline mode without requiring any IP address changes on existing devices. In VWire mode, the firewall acts as a Layer 2 bump in the wire, forwarding traffic between two interfaces based on MAC addresses without participating in routing or requiring IP configuration on the firewall interfaces themselves.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This PCNSE practice question is part of Courseiva's free Palo Alto Networks 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 PCNSE exam.
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