Palo Alto Networks Certified Network Security Engineer (PCNSE)Core ConceptsEasy
A network security administrator needs to configure a Palo Alto Networks firewall to allow traffic between two internal zones (e.g., 'Trust' and 'Servers'). The administrator intends to use a Layer 3 interface for routing between these zones. Which type of interface should be configured on the firewall to achieve this?
- ATap Interface
- BLayer 2 Interface
- CVirtual Wire Interface
- DLayer 3 Interface
Show answer & explanationAnswer & explanation
Correct answer: D. Layer 3 Interface
A Layer 3 interface on a Palo Alto Networks firewall functions as a traditional routed interface. It has an IP address, can participate in routing protocols, and typically connects to different subnets or zones, enabling the firewall to perform routing and security enforcement between them. This is the correct choice for routing traffic between distinct internal zones.
Why the other options are wrong
- A. A Tap interface is used for passive monitoring of traffic and does not forward or block traffic.
- B. A Layer 2 interface forwards traffic based on MAC addresses within the same broadcast domain and does not perform routing between different subnets/zones.
- C. A Virtual Wire interface (or 'bump-in-the-wire') transparently connects two network segments without requiring an IP address, primarily for inline inspection without routing.
Palo Alto Layer 3 Interface
A Layer 3 interface on a Palo Alto Networks firewall is a routed interface that has an IP address, participates in routing, and enables the firewall to connect to and enforce policies between different IP subnets or security zones.
- Functions as a routed interface.
- Has an IP address and can participate in routing protocols.
- Connects different subnets/security zones.
Memory trick: Layer 3 for Routing, Layer 2 for Switching, Virtual Wire for Transparency.