PCNSE Core Concepts and Architecture Practice Question
A company is deploying a Palo Alto Networks firewall in an existing Layer 2 switched environment. They need to inspect traffic between VLAN 10 and VLAN 20 without changing the IP addresses of hosts and without performing any routing. Which firewall mode should be used?
⚠ Common exam trap
Watch out — candidates often confuse Virtual Wire mode with Transparent mode, assuming Virtual Wire can handle VLANs, but Virtual Wire does not support VLAN subinterfaces or inter-VLAN inspection, making it unsuitable for this requirement.
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
✓
Transparent (Layer 2)
Transparent (Layer 2) mode allows the firewall to operate as a Layer 2 bridge, inspecting traffic between VLAN 10 and VLAN 20 without requiring any IP address changes or routing. The firewall forwards frames based on MAC addresses, preserving the existing IP subnet and host configurations, which is ideal for inserting security into an existing switched environment.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Virtual Wire
Why it's wrong here
Virtual Wire mode is used for transparent inline inspection on the same subnet; it cannot handle multiple VLANs without additional configuration like subinterfaces, but it does not perform routing between VLANs.
- ✗
Tap mode
Why it's wrong here
Tap mode is passive monitoring only; traffic flows through the firewall but no inspection or control is applied.
- ✓
Transparent (Layer 2)
Why this is correct
Correct. Transparent mode bridges VLANs at Layer 2, enabling inspection without IP changes.
- ✗
Layer 3
Why it's wrong here
Layer 3 mode requires IP addresses on interfaces and performs routing, which changes the network topology.
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 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.