hardMultiple Choice
PCNSA Practice Question: Two Palo Alto Networks firewalls are configured…
Two Palo Alto Networks firewalls are configured in an active/passive high-availability pair. During a failover event, the passive firewall becomes active but the session table is empty. What is the most likely cause?
⚠ Common exam trap
Many exam-takers assume session state is automatically synchronized in an HA pair, but Palo Alto Networks requires explicit configuration of session synchronization via the HA setup, and failing to enable it leaves the passive firewall without session data.
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
✓
Session synchronization is not configured
In an active/passive high-availability pair, session synchronization must be explicitly configured to replicate session state from the active firewall to the passive firewall. Without this configuration, the passive firewall has no session table when it becomes active, causing all existing connections to be dropped. This is the most direct cause of an empty session table after failover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Session synchronization is not configured
Why this is correct
Without session synchronisation enabled, the passive peer never receives session state, so after failover its session table is empty and established flows drop. Enabling HA session synchronisation satisfies the continuity requirement the active/passive pair depends on.
- ✗
The preemptive mode is disabled
Why it's wrong here
Preemptive mode controls failback, not session synchronization.
- ✗
Heartbeat failure caused the failover to be incomplete
Why it's wrong here
A heartbeat failure triggers failover rather than leaving it incomplete; the passive device still assumes the active role and forwards traffic. It tempts because heartbeat loss is the usual trigger for HA transition, and would be correct if the stem described the passive firewall failing to take over at all.
- ✗
The sessions timed out during the failover
Why it's wrong here
Failover completes in seconds, so established sessions would not expire unless the HA configuration already had very short timeouts. It tempts because session ageing is a genuine cause of empty tables, and would be correct if the stem described a prolonged outage exceeding the configured timeout values.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNSA 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 PCNSA exam.