In FortiOS 7.6, HA cluster heartbeat IP addresses are automatically managed by FortiGate and play a critical role in cluster communication and synchronization.

Correct statements

A. Heartbeat IP addresses are used to distinguish between cluster members.

Correct

FortiGate assigns unique heartbeat IP addresses (link-local addresses in the 169.254.0.0/16 range) to each HA member.

These addresses are used for:

Cluster member identification

Health checks

Synchronization traffic

This allows FortiGate units to uniquely identify and communicate with each other inside the HA cluster.

C. A change in the heartbeat IP address happens when a FortiGate device joins or leaves the cluster.

Correct

Heartbeat IPs are dynamically assigned.

When:

A new FortiGate joins the cluster, or

A member leaves or fails,

FortiGate may reassign heartbeat IP addresses to maintain unique identification among members.

This behavior is documented in the FortiOS HA operation and troubleshooting guides.

Why the other options are incorrect

B. The heartbeat interface of the primary device is always assigned IP address 169.254.0.1.

Incorrect

There is no fixed or guaranteed heartbeat IP (such as 169.254.0.1) for the primary unit.

Heartbeat IP assignment is dynamic, not role-based.

D. Heartbeat interfaces have virtual IP addresses that are manually assigned.

Incorrect

Heartbeat IP addresses are:

Automatically assigned

Link-local

Administrators do not manually configure heartbeat IP addresses.