NSE4 System and Network Administration Practice Question
A FortiGate is configured in an HA active-passive cluster. The primary unit fails. After the secondary takes over, a policy route configured on the primary is not working. What is the MOST likely reason?
⚠ Common exam trap
Candidates often assume HA synchronizes everything perfectly, but they overlook that interface-dependent objects like policy routes can break if the physical interface mapping differs between cluster members.
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
✓
The policy route references an interface that does not exist on the new primary
When a FortiGate HA cluster fails over, the new primary unit assumes the configuration synchronized from the original primary. However, if a policy route references a specific interface (e.g., port1 or a VLAN subinterface) that is physically present on the failed unit but not on the new primary (or has a different name/index), the policy route will fail because the kernel cannot resolve the egress interface. FortiGate HA synchronizes the configuration, but interface mappings must match across cluster members for policy routes to work 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.
- ✗
The secondary unit does not support policy routes
Why it's wrong here
The claim that the secondary unit does not support policy routes is incorrect. FortiGate policy routing is a core feature available on every HA member regardless of its active or passive role. In an active-passive cluster, the standby unit runs the same FortiGate operating system and holds the same configuration, so when it assumes the primary role it can enforce policy routes identically to the previous primary.
- ✗
The policy route configuration is not synchronized in HA
Why it's wrong here
In a FortiGate HA cluster, configuration synchronization is continuous and comprehensive, so policy routes are definitely synced to the secondary unit. The failure is not due to missing configuration but to a runtime dependency that the synced configuration cannot satisfy on the new primary. If anything, the policy route exists in the config but cannot be applied because of interface availability.
- ✗
The HA cluster requires a reboot after failover
Why it's wrong here
HA failover in FortiGate is designed to be seamless and does not require any reboot of the cluster or the devices. The standby unit continuously receives heartbeat signals and is fully initialized with the current configuration and synchronized sessions; on failure, it simply transitions to active state. Rebooting would defeat the purpose of high availability and cause unnecessary downtime, so it is never a normal failover step.
- ✓
The policy route references an interface that does not exist on the new primary
Why this is correct
The most plausible cause is that the policy route specifies a destination or source interface that only exists on the original primary, not on the new primary. In an HA cluster, configuration is synced as a whole, but if the physical interfaces are named differently on the secondary (for example, due to different hardware models) or the interface is a VLAN/subinterface whose underlying port is not present, the policy route becomes invalid after failover. FortiGate will then skip or deactivate the route because the referenced interface is missing, resulting in traffic not being routed as expected.
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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.