Explanation/Reference: https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/c/sw/gui/config/guide/4_1/ b_Cisco_UCS_C-series_GUI_Configuration_Guide_41/b_Cisco_UCS_C- series_GUI_Configuration_Guide_41_chapter_01.html

In a Cisco UCS environment, ensuring high availability (HA) between clustered Fabric Interconnects is essential for operational resilience. There are specific commands used to check the HA state of these Fabric Interconnects:
show cluster state:
This command provides a basic view of the cluster status between the two Fabric Interconnects. It shows whether the cluster is in a primary or subordinate state and provides information about each Fabric Interconnect's role. This is a fundamental command used for checking the general state of the cluster.
show cluster extended-state:
This command provides a more detailed view of the cluster's HA status, offering extended information about the cluster's synchronization status, heartbeat status, and any potential issues. It helps in diagnosing more granular details of the cluster's health and HA status.
Explanation of Incorrect Options:
show cluster HA state and show cluster HA status: These are not valid commands in the Cisco UCS command-line interface.
show cluster state extended: While similar in wording, this is also not a valid command in Cisco UCS for viewing HA status.
Summary:
To verify the high availability state between two clustered Fabric Interconnects, use show cluster state for a general status overview and show cluster extended-state for a detailed diagnostic view. These commands are essential for UCS administrators to ensure that the Fabric Interconnects are operating in a healthy and synchronized HA configuration.