PCNSE Troubleshoot Practice Question
In an active/passive HA pair, the passive firewall shows state 'non-functioning'. Both firewalls are running PAN-OS 10.1.5. What is the most likely cause?
⚠ Common exam trap
Candidates often assume a heartbeat failure or license issue causes the 'non-functioning' state, but the specific PAN-OS version mismatch is the only condition that directly triggers this exact HA state in an active/passive pair.
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
✓
Firmware version mismatch (one firewall is on 10.1.4)
In an active/passive HA pair, both firewalls must run the same PAN-OS version to form a healthy HA connection. If one firewall is on 10.1.5 and the other on 10.1.4, the passive firewall will show a 'non-functioning' state because the HA configuration synchronization and keepalive mechanisms detect a version mismatch, preventing the HA pair from establishing correctly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Heartbeat interface down
Why it's wrong here
A down heartbeat interface would show 'not synchronized' or 'initial', not 'non-functioning'.
- ✓
Firmware version mismatch (one firewall is on 10.1.4)
Why this is correct
HA requires exact PAN-OS version match. Even a minor patch difference can cause synchronization failure.
- ✗
Management IP mismatch
Why it's wrong here
Management IP addresses are not required to match; they are used for out-of-band management.
- ✗
License mismatch
Why it's wrong here
License mismatch does not prevent HA formation; only feature availability may differ.
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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.