NSE4 System and Network Administration Practice Question
An organization has two FortiGate units in an HA cluster. They need to perform a firmware upgrade on the primary unit without causing a failover. Which procedure should be followed?
⚠ Common exam trap
Test-takers frequently assume upgrading the primary first is safe because the secondary will synchronize, but they overlook that the primary reboot triggers an automatic failover, which is not a 'graceful' upgrade path.
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
✓
Upgrade the secondary unit first, then perform a graceful failover, then upgrade the original primary
In an HA cluster, upgrading the secondary unit first ensures that the primary remains active and can take over if the upgrade fails. After the secondary is upgraded and stable, a graceful failover is performed to make it the new primary, allowing the original primary to be upgraded without causing an unplanned failover or service interruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Upgrade the primary unit first, then the secondary will automatically synchronize
Why it's wrong here
Upgrading the primary unit while the secondary remains on the old firmware is unsupported because FortiGate HA requires both cluster members to run identical firmware images. When the primary reboots to install the new FortiOS, the secondary takes over with the old firmware, but the two units cannot synchronize sessions or configuration due to version mismatch. This may cause a split-brain scenario, service disruption, and the cluster may fail to rejoin, leaving you with an unstable network.
- ✗
Upgrade both units simultaneously using the GUI
Why it's wrong here
Selecting both units in the GUI for a simultaneous upgrade is not a valid HA procedure because FortiGate does not orchestrate a synchronized reboot across cluster members. If both firewalls reboot at the same time, the cluster loses all forwarding capacity, causing a complete network outage. Even if the GUI attempts to upgrade them sequentially, any unplanned reboot during the process leaves the cluster vulnerable. The proper approach is a staggered upgrade, not parallel.
- ✗
Disable HA, upgrade both, then re-enable HA
Why it's wrong here
Disabling HA before the upgrade strips away redundancy, and if the sole active firewall fails during the upgrade window, the network goes down with no automatic failover. Re-enabling HA afterward requires careful re-synchronization of configuration and can result in inconsistent sessions if the upgrade changed settings. The entire cluster is also exposed to misconfiguration because the two units are no longer sharing state. Thus, this method introduces an unnecessary risk of outage and is not a best practice.
- ✓
Upgrade the secondary unit first, then perform a graceful failover, then upgrade the original primary
Why this is correct
Upgrade the secondary (standby) unit first so the active primary continues to pass traffic throughout the upgrade process; the secondary then joins the HA cluster with the new firmware. Once the secondary is fully upgraded and synchronized, perform a graceful failover to make it the new primary, which transfers the active sessions to the upgraded unit. Finally, upgrade the original primary (now standby) during a maintenance window, ensuring only one unit is offline at a time and no traffic is dropped.
Go deeper
Related to this question
About these practice questions
This NSE4 question is part of Courseiva's 773-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
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.