According to the FortiOS 7.6 High Availability (HA) Administration Guide and FGCP (FortiGate Clustering Protocol) requirements, the correct answers are B and D.
FGCP HA Cluster Mandatory Requirements (FortiOS 7.6)
When forming an HA cluster using FGCP, FortiGate devices must meet several strict compatibility and configuration requirements. Among the options given, the following two are mandatory:
✅ B. They must have the same number of configured VDOMs
In FortiOS HA, all cluster members must have the same VDOM configuration.
This includes:
Same number of VDOMs
Same VDOM names
This is required so configuration synchronization can occur correctly between members.
If VDOM counts differ, HA formation will fail.
✔ This is explicitly required and documented.
✅ D. They must have the same HA group ID
The HA group ID uniquely identifies an HA cluster on the network.
All FortiGate units intended to join the same cluster must share the same HA group ID.
If the group IDs differ, devices will not recognize each other as cluster peers.
✔ This is a fundamental FGCP requirement.
Why the Other Options Are Incorrect
❌ A. They must have the same hard drive configuration
Hard drive presence or size does not have to match for FGCP HA to function.
Disk differences may affect logging behavior, but they do not prevent HA cluster formation.
Therefore, this is not a required condition.
❌ C. They must have the heartbeat interfaces in the same subnet
Heartbeat interfaces must be:
They do not require IP addressing or being in the same IP subnet.
In many deployments, heartbeat interfaces have no IP addresses at all.
Therefore, “same subnet” is not a documented requirement.
