Palo Alto Networks Certified Network Security Administrator (PCNSA)Initial Configuration and ManagementHard
A network administrator is configuring network interfaces on a Palo Alto Networks firewall. They want to create a subinterface on ethernet1/1 to handle traffic for VLAN 100. Which of the following statements is true regarding this configuration?
- AThe subinterface for VLAN 100 will have an interface name like ethernet1/1.100.
- BThe subinterface will be configured as a Layer 2 interface and assigned to a VLAN object.
- CA separate virtual router must be created for each VLAN subinterface.
- DThe physical interface ethernet1/1 must be configured as a Layer 3 interface type.
Show answer & explanationAnswer & explanation
Correct answer: A. The subinterface for VLAN 100 will have an interface name like ethernet1/1.100.
When creating a subinterface for a specific VLAN on a Palo Alto Networks firewall, the naming convention typically appends the VLAN ID to the physical interface name. For example, a subinterface for VLAN 100 on ethernet1/1 would be named ethernet1/1.100.
Why the other options are wrong
- B. Subinterfaces for routing (Layer 3) are common for VLANs, not necessarily Layer 2. They don't get 'assigned to a VLAN object' in the same way, but rather have a VLAN tag configured on them.
- C. Multiple VLAN subinterfaces can belong to the same virtual router, allowing them to route traffic between each other if policies permit. A separate virtual router is not required for each.
- D. The physical interface ethernet1/1 can be Layer 2 or Layer 3 to host subinterfaces; it does not strictly have to be Layer 3.
Palo Alto Subinterface Naming
Palo Alto Networks subinterfaces are typically named by appending the VLAN ID to the physical interface name (e.g., ethernet1/1.100) and are used for VLAN tagging.
- Used to handle tagged VLAN traffic.
- Can be Layer 2 or Layer 3.
- Commonly used with Virtual Routers for inter-VLAN routing.
Memory trick: VLAN's number gets hitched to the interface name, like a dot-wedding on the network game!