This PCNSE practice question tests your understanding of managing troubleshooting and high availability. 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 network engineer is troubleshooting an HA pair where both firewalls show as 'active' in the HA state. What is this condition called?
Link failure
Why wrong: Link failure is a condition that can cause HA state issues but is not the state itself.
Active/Active
This is the correct term for both firewalls being active.
Passive/Passive
Why wrong: This is when both are passive.
Split brain
Why wrong: Split brain is when both think they are active, but the term used here is active/active.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Active/Active
In an active/passive HA pair, only one firewall should be active at a time. When both firewalls show as 'active', this is known as a split-brain condition. It occurs when the HA heartbeat link fails and each firewall assumes the other is down, causing both to transition to the active state and process traffic independently.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Link failure
Why it's wrong here
Link failure is a condition that can cause HA state issues but is not the state itself.
Active/Active
Why this is correct
This is the correct term for both firewalls being active.
Related concept
Read the scenario before looking for a memorised answer.
Passive/Passive
Why it's wrong here
This is when both are passive.
Split brain
Why it's wrong here
Split brain is when both think they are active, but the term used here is active/active.
Common exam traps
The trap here is that candidates confuse 'split brain' with 'active/active' mode, but active/active is a legitimate configuration where both firewalls actively forward traffic for different virtual routers or security zones, whereas split brain is an unintended failure state.
Detailed technical explanation
Split brain typically results from a complete loss of HA1 (control link) and HA2 (data link) connectivity while management interfaces remain reachable. The firewalls rely on hello packets sent every 1 second over the HA1 link; after three missed hello packets (3-second hold timer), a firewall declares the peer dead and transitions to active. In production, this can cause duplicate IP addresses, asymmetric routing, and state table mismatches, requiring manual intervention to resolve.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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
Managing Troubleshooting and High Availability — This question tests Managing Troubleshooting and High Availability — Read the scenario before looking for a memorised answer..
The correct answer is: Active/Active — In an active/passive HA pair, only one firewall should be active at a time. When both firewalls show as 'active', this is known as a split-brain condition. It occurs when the HA heartbeat link fails and each firewall assumes the other is down, causing both to transition to the active state and process traffic independently.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 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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