A). A change in the virtual IP address happens when a FortiGate device joins or leaves the cluster: When a FortiGate device joins or leaves the High Availability (HA) cluster, there can be a change in the virtual IP address. The virtual IP address is typically associated with the primary unit in the cluster, and if there's a change in the cluster composition, the virtual IP may be reassigned to the new primary unit.
B). Virtual IP addresses are used to distinguish between cluster members:
Virtual IP addresses are indeed used to distinguish between cluster members. In an HA cluster, there is a virtual IP address that is associated with the primary unit. This virtual IP address serves as the gateway for devices on the network, and it helps ensure seamless failover in the event of a primary unit failure.
The other statements (C and D) are not accurate:
C). Heartbeat interfaces have virtual IP addresses that are manually assigned:
This statement is not correct. Heartbeat interfaces are used for communication between cluster members to monitor each other's status. Virtual IP addresses are typically associated with the cluster and are automatically assigned or reassigned based on the cluster configuration.
D). The primary device in the cluster is always assigned IP address 169.254.0.1:
This statement is not correct. The primary device in the cluster is assigned the virtual IP address associated with the cluster. The IP address 169.254.0.1 is typically reserved for certain link-local purposes and is not a standard IP address for the primary device in an HA cluster.
The correct statements regarding FortiGate HA cluster virtual IP addresses are:
A). A change in the virtual IP address happens when a FortiGate device joins or leaves the cluster.
B). Virtual IP addresses are used to distinguish between cluster members.
Extra
A). When a FortiGate device joins or leaves the cluster, the virtual IP address associated with the cluster may change. The virtual IP address is assigned to the primary device in the cluster, and if that device fails, the virtual IP address will failover to the secondary device.
B). Virtual IP addresses are used to distinguish between cluster members. Each device in the cluster has a unique physical IP address, but they share a virtual IP address that is used by clients to communicate with the cluster as a whole. The virtual IP address is used to identify the cluster, and clients use it to connect to the cluster rather than connecting to a specific device.
A change in the heartbeat ip addresses might happend when a fortigate device joins or leaves the cluster. In those cases, the cluster renegotiates the heartsbeat ip address assignment, this time taking into account the serial number of any new device, or removing the serial number of any device that left the cluster & cluster uses these virtual ip addressesto: Distinguish the cluster member