- A
Verify the physical connectivity and configuration of the HA2 link, as session synchronization failure can cause the passive node to be non-functional.
Why wrong: HA2 is for session sync; its failure typically causes sync issues but not a 'non-functional' state. The link is a dedicated out-of-band connection, so it is unlikely to be the cause.
- B
Reboot the passive firewall to attempt to re-establish HA communication.
Why wrong: Rebooting is disruptive and does not address the underlying configuration issue that caused the non-functional state.
- C
Check the logs on the passive firewall for new critical events during the switch replacement.
Why wrong: While logs are useful, this is a secondary step; the most likely issue is path monitoring misconfiguration triggered by the switch replacement.
- D
Review the path monitoring configuration on both firewalls to ensure that the AE link to the new switches is correctly monitored for failover.
Path monitoring checks data plane connectivity; if the monitored interface is down or misconfigured, the passive firewall goes non-functional. The switch replacement likely altered link characteristics, making the monitored path appear failed.
Troubleshooting Passive Firewall Non-Functional State Due to Path Monitoring
This PCNSE practice question tests your understanding of managing troubleshooting and high availability. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A large enterprise uses a pair of PA-5250 firewalls in an active/passive high availability configuration to protect their data center. The firewalls are connected to two upstream switches via aggregate Ethernet (AE) interfaces. The network team recently replaced the upstream switches, and since then, the passive firewall has gone into a 'non-functional' state. The active firewall shows no issues. The HA1 link is a direct cable connection between the firewalls, and HA2 is an out-of-band dedicated link. The administrative status of both firewalls is 'active-active' in the HA monitoring, but only one firewall is actually forwarding traffic. The team needs to restore proper HA operation. Which action should the team take first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
Review the path monitoring configuration on both firewalls to ensure that the AE link to the new switches is correctly monitored for failover.
Option D is correct because path monitoring is used in active/passive HA to detect failures of monitored interfaces (like the AE links to the new switches). If the passive firewall's path monitoring configuration does not match the new switch interfaces or if the monitored AE link is down, the passive firewall will enter a 'non-functional' state to prevent it from becoming active with a broken path. The active firewall remains unaffected because it is already forwarding traffic and its path monitoring status is healthy.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Verify the physical connectivity and configuration of the HA2 link, as session synchronization failure can cause the passive node to be non-functional.
Why it's wrong here
HA2 is for session sync; its failure typically causes sync issues but not a 'non-functional' state. The link is a dedicated out-of-band connection, so it is unlikely to be the cause.
- ✗
Reboot the passive firewall to attempt to re-establish HA communication.
Why it's wrong here
Rebooting is disruptive and does not address the underlying configuration issue that caused the non-functional state.
- ✗
Check the logs on the passive firewall for new critical events during the switch replacement.
Why it's wrong here
While logs are useful, this is a secondary step; the most likely issue is path monitoring misconfiguration triggered by the switch replacement.
- ✓
Review the path monitoring configuration on both firewalls to ensure that the AE link to the new switches is correctly monitored for failover.
Why this is correct
Path monitoring checks data plane connectivity; if the monitored interface is down or misconfigured, the passive firewall goes non-functional. The switch replacement likely altered link characteristics, making the monitored path appear failed.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the passive firewall's 'non-functional' state is caused by HA link issues (HA1 or HA2) or session synchronization failures, when in fact it is typically due to path monitoring detecting a failed interface on the passive node.
Detailed technical explanation
How to think about this question
Path monitoring in PAN-OS uses a combination of interface monitoring and path monitoring groups; if a monitored interface goes down, the firewall's path monitoring status becomes 'failed', and in active/passive HA, the passive firewall will not transition to active unless its path monitoring is healthy. The 'non-functional' state specifically indicates that the firewall cannot participate in HA due to a critical failure, often triggered by path monitoring or link monitoring failures. In real-world scenarios, replacing upstream switches can change interface naming, VLAN configurations, or link status, causing the passive firewall to see its monitored AE interface as down while the active firewall's path remains up.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the PCNSE exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCNSE question test?
Managing Troubleshooting and High Availability — This question tests Managing Troubleshooting and High Availability — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Review the path monitoring configuration on both firewalls to ensure that the AE link to the new switches is correctly monitored for failover. — Option D is correct because path monitoring is used in active/passive HA to detect failures of monitored interfaces (like the AE links to the new switches). If the passive firewall's path monitoring configuration does not match the new switch interfaces or if the monitored AE link is down, the passive firewall will enter a 'non-functional' state to prevent it from becoming active with a broken path. The active firewall remains unaffected because it is already forwarding traffic and its path monitoring status is healthy.
What should I do if I get this PCNSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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.
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