- A
The session table is not synchronized between HA peers.
Without session synchronization, the new active firewall does not have existing sessions, causing traffic drops.
- B
The passive firewall's routing table is not synchronized.
Why wrong: HA synchronizes routing tables, so this should not be an issue.
- C
The virtual router is not configured to use the virtual IPs.
Why wrong: Virtual IPs are automatically assigned to the virtual router in HA.
- D
The HA configuration does not include the virtual router.
Why wrong: HA synchronizes virtual router configuration between peers.
Question 3 of 516
PCNSE Manage, Monitor and Operate Practice Question
This PCNSE practice question tests your understanding of manage, monitor and operate. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 firewall is configured with two virtual routers in an active/passive HA pair. The active firewall fails over, and after failover, traffic is not passing through the new active firewall. The interface IP addresses are configured as virtual IPs. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 session table is not synchronized between HA peers.
In an active/passive HA pair with virtual IPs, session table synchronization is required for the passive firewall to take over active sessions seamlessly after a failover. If session synchronization is not enabled or fails, the new active firewall will not have the session state for existing traffic, causing it to drop packets that belong to those sessions. This is the most likely cause because the interface IPs are virtual, so the routing and interface configuration are already in place, but the session state is missing.
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.
- ✓
The session table is not synchronized between HA peers.
Why this is correct
Without session synchronization, the new active firewall does not have existing sessions, causing traffic drops.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The passive firewall's routing table is not synchronized.
Why it's wrong here
HA synchronizes routing tables, so this should not be an issue.
- ✗
The virtual router is not configured to use the virtual IPs.
Why it's wrong here
Virtual IPs are automatically assigned to the virtual router in HA.
- ✗
The HA configuration does not include the virtual router.
Why it's wrong here
HA synchronizes virtual router configuration between peers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume routing table synchronization is the issue because traffic stops, but PAN-OS automatically syncs routing tables via HA2, while session synchronization is a separate, optional feature that must be explicitly enabled and is frequently overlooked.
Detailed technical explanation
How to think about this question
Session synchronization in PAN-OS HA uses the HA3 (data link) or HA2 (control link) to replicate session entries from the active to the passive firewall. The session table contains Layer 4 state information (e.g., TCP sequence numbers, NAT translations, application IDs) that must be identical on both peers for seamless failover. In real-world scenarios, if session sync is disabled or the HA3 link is down, the passive firewall will drop all existing connections after failover, requiring clients to re-establish sessions, which can cause significant disruption.
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.
Visual reference
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this PCNSE question test?
Manage, Monitor and Operate — This question tests Manage, Monitor and Operate — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The session table is not synchronized between HA peers. — In an active/passive HA pair with virtual IPs, session table synchronization is required for the passive firewall to take over active sessions seamlessly after a failover. If session synchronization is not enabled or fails, the new active firewall will not have the session state for existing traffic, causing it to drop packets that belong to those sessions. This is the most likely cause because the interface IPs are virtual, so the routing and interface configuration are already in place, but the session state is missing.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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