PCNSE Practice Question: Managing Troubleshooting and High Availability
An engineer is troubleshooting an active/passive HA pair where the passive firewall is not receiving session synchronization updates from the active firewall. The HA2 link is up, and the HA1 link is healthy. The engineer checks the HA configuration and sees that the HA2 interface is configured with an IP address, and session synchronization is enabled. What is the most likely cause of the synchronization failure?
⚠ Common exam trap
The trap here is overlooking the subnet requirement for HA2; engineers often focus on link status and session sync enablement but forget that IP addressing must be in the same subnet.
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
✓
The HA2 interface is configured in a different subnet on each firewall.
The HA2 interfaces must be in the same subnet for session synchronization to occur. If they are in different subnets, the firewalls cannot establish a direct connection for synchronization, even if the link is physically up. This is a common configuration error that leads to synchronization failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Session synchronization is disabled on the active firewall.
Why it's wrong here
The scenario states that session synchronization is enabled. If it were disabled, that would certainly cause the failure, but the engineer has already verified it is enabled. Therefore, this cannot be the cause. The issue must lie elsewhere, such as subnet mismatch.
- ✓
The HA2 interface is configured in a different subnet on each firewall.
Why this is correct
For HA2 synchronization to work, the HA2 interfaces on both firewalls must be in the same subnet. If they are in different subnets, they cannot communicate directly, and session synchronization will fail. This is a common misconfiguration that can prevent the passive firewall from receiving session updates.
- ✗
The HA2 interface is not assigned to a security zone.
Why it's wrong here
HA2 interfaces do not require assignment to a security zone; they operate outside the security policy framework. Zone assignment is irrelevant for HA2 functionality. The synchronization failure is more likely due to a network-level misconfiguration such as incorrect subnetting.
- ✗
The HA2 interface is configured as a Layer 2 interface instead of Layer 3.
Why it's wrong here
HA2 interfaces must be Layer 3 to support IP addressing and synchronization traffic. If configured as Layer 2, they would not have IP addresses and synchronization would fail. However, the scenario states that the HA2 interface is configured with an IP address, implying it is Layer 3. Thus, this is not the cause.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Palo Alto Networks exam blueprint
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.