NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. 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.
An administrator configures two FortiGate units in an active-passive HA cluster. After a failover, some existing TCP sessions are dropped. What is the most likely reason for this behavior?
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 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 enabled
In an active-passive HA cluster, session synchronization must be explicitly enabled to replicate TCP session state from the primary unit to the backup unit. Without session sync, the backup unit has no knowledge of existing TCP sessions after a failover, causing those sessions to be dropped because the new primary cannot match incoming packets to any session table entry.
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.
✓
Session synchronization is not enabled
Why this is correct
Session synchronization must be enabled to maintain TCP sessions across failover.
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 failover time is too slow
Why it's wrong here
Failover time may cause brief interruption, but sessions would still be lost if not synced.
✗
The FortiGate units are running different firmware versions
Why it's wrong here
Different firmware would prevent HA formation altogether.
✗
The HA cluster is using a virtual MAC address
Why it's wrong here
Virtual MAC ensures seamless layer 2 connectivity, but sessions are still lost without sync.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume HA automatically synchronizes all state information, but FortiGate requires explicit configuration of session synchronization (via 'set session-pickup enable' in the HA settings) to preserve existing TCP sessions after a failover.
Detailed technical explanation
How to think about this question
Session synchronization in FortiGate HA uses the session sync daemon to periodically send session table updates over the HA heartbeat link (typically using UDP port 703). For TCP sessions, the sync interval and the number of retransmissions can be tuned with commands like 'set session-sync-dev' and 'set session-pickup'. In real-world deployments, failing to enable session synchronization is a common oversight that leads to dropped VoIP or database connections during failover, as these long-lived TCP sessions are critical for application continuity.
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 NSE4 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Session synchronization is not enabled — In an active-passive HA cluster, session synchronization must be explicitly enabled to replicate TCP session state from the primary unit to the backup unit. Without session sync, the backup unit has no knowledge of existing TCP sessions after a failover, causing those sessions to be dropped because the new primary cannot match incoming packets to any session table entry.
What should I do if I get this NSE4 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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This NSE4 practice question is part of Courseiva's free Fortinet 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 NSE4 exam.
Question Discussion
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