NSE4 High Availability and Diagnostics Practice Question
An administrator notices that the FortiGate HA cluster has two units, but only one is shown as 'primary' and the other as 'standby'. The administrator did not configure any load balancing. Which HA mode is in use?
⚠ Common exam trap
NSE4 often tests the visual signature of HA modes — one primary plus one standby equals active-passive — so candidates confuse it with active-active or invent a 'load-balanced' mode that does not exist.
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
✓
Active-passive
In active-passive HA mode, one FortiGate unit is the primary (active) and the other is the standby (passive), with no traffic load balancing between them. The scenario describes exactly one primary and one standby with no load balancing configured, which matches active-passive. Active-active would show both units processing traffic, and load-balanced cluster is not a FortiGate HA mode.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Active-passive
Why this is correct
Active-passive is the standard FortiGate HA mode in which one cluster unit holds the primary/active role and processes all production traffic, while the second unit remains in standby, synchronizing configuration and (if session pickup is enabled) session state via the dedicated HA heartbeat link. When the active unit fails or loses heartbeats, the standby unit is promoted to active and takes over the virtual cluster interfaces, providing transparent failover with minimal disruption.
- ✗
Load-balanced cluster
Why it's wrong here
FortiGate does not offer a separate HA mode called 'load-balanced cluster'; load balancing is only a scheduling option within active-active HA, where every cluster member actively forwards traffic and new sessions are distributed among them. Since the observed cluster has a standby unit rather than all members actively forwarding, it cannot be in a load-balanced configuration, because load-balanced operation requires all units to be active and handling traffic simultaneously.
- ✗
Standalone
Why it's wrong here
Standalone is not an HA mode at all; it describes a single FortiGate unit operating independently with no HA peer, no heartbeat interface, and no automatic failover capability. The administrator is observing an HA cluster, which by definition consists of multiple FortiGate units exchanging heartbeat messages and maintaining cluster roles, so 'standalone' is categorically impossible for a functioning HA deployment.
- ✗
Active-active
Why it's wrong here
Active-active HA is a FortiGate HA mode in which both cluster units are active and process data traffic concurrently, using a scheduling algorithm such as least-connection, source-IP hash, or round-robin to distribute new sessions across the members. In the described cluster, one unit is in standby and only one unit handles traffic, which directly contradicts active-active's core requirement that all cluster members be active; active-active is a distinct mode from active-passive, and the observed standby role identifies the cluster as active-passive.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Fortinet exam blueprint
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.