NSE4 High Availability and Diagnostics Practice Question
In an active-active HA cluster, what is the purpose of the 'session sync' configuration?
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
✓
To replicate session state so that if one unit fails, another can take over without interruption
Session sync ensures that sessions are shared between cluster units so that any unit can handle traffic for a given session.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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To synchronize configuration changes between cluster members
Why it's wrong here
Configuration synchronization is a management-plane process in Fortinet HA that copies the master configuration from the primary to secondary units, either at startup or when settings change. Session synchronization is a separate data-plane mechanism that replicates only session table entries, such as NAT and TCP state, in real time. Mixing these two functions is a common misunderstanding, as they serve entirely distinct purposes.
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To balance the number of sessions across cluster members
Why it's wrong here
Load balancing in an active-active cluster is performed by the cluster's scheduling algorithm, which decides where each new connection is placed based on policies like round-robin or source IP hashing. Session synchronization does not distribute sessions; it merely mirrors the state of already-established sessions onto peer units. Therefore, session sync cannot affect how many sessions each unit handles—only the scheduler determines that distribution.
- ✓
To replicate session state so that if one unit fails, another can take over without interruption
Why this is correct
Session synchronization replicates the full state of active sessions—including TCP sequence numbers, NAT translations, and timers—from the unit that owns the session to every other member of the cluster. If the owning unit fails, a peer that has an identical session record can immediately resume forwarding traffic without requiring clients to re-establish their connections. This stateful takeover is critical for seamless failover in high-availability clusters.
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To synchronize the time between cluster members
Why it's wrong here
Time synchronization in a Fortinet HA cluster is accomplished via NTP configuration or by having the primary unit propagate its system clock to secondaries over the HA heartbeat link. Session synchronization is unrelated to time; it transports session data, not clock updates. While synchronized time is important for log correlation and authentication, it is not a function of the session sync channel.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.