PCNSE Core Concepts and Architecture Practice Question
Two Palo Alto Networks firewalls are configured in an active/passive HA pair. During a scheduled maintenance, the network team reboots both firewalls simultaneously. After reboot, both firewalls appear as 'active' in the HA state. What is the most likely cause and the correct troubleshooting step?
⚠ Common exam trap
Test-takers frequently assume simultaneous reboot causes a priority tie, but the real issue is the missing heartbeat link, which prevents the firewalls from detecting each other's state after reboot.
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 heartbeat link between the firewalls is missing or fails, causing each to believe the other is down. The correct step is to restore the heartbeat link and then set the appropriate firewall as passive.
In an active/passive HA pair, each firewall monitors the peer's health via the heartbeat link. If the heartbeat link fails, each firewall assumes the peer is down and transitions to active state to ensure traffic continuity. Simultaneous reboot does not cause both to become active unless the heartbeat link is absent or broken; restoring the heartbeat link and forcing one firewall to passive resolves the split-brain scenario.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Both firewalls have the same priority; the tie is broken by serial number, but due to simultaneous reboot, both came up as active. The solution is to reboot one firewall.
Why it's wrong here
Priority and serial number determine active, but simultaneous reboot should still result in one active based on tie-breaker; split-brain typically indicates heartbeat failure.
- ✗
The HA configuration is set to active/active mode instead of active/passive.
Why it's wrong here
In active/active, both are always active, but the question says active/passive.
- ✓
The heartbeat link between the firewalls is missing or fails, causing each to believe the other is down. The correct step is to restore the heartbeat link and then set the appropriate firewall as passive.
Why this is correct
Split-brain is usually due to lost heartbeat; restoring it and setting one as passive resolves.
- ✗
The heartbeat interfaces are not configured on each firewall.
Why it's wrong here
If heartbeat interfaces are configured but down, it would cause split-brain; but the correct fix is to first check them.
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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.