In an HA pair, the secondary appliance shows state Unknown due to which issue?

• A. RPC nodes are incorrectly configured
• B. Synchronization on the secondary is disabled
• C. TCP port 22 is disabled between appliances
• D. Both appliances were configured as primary

Answer: (A)

In an HA pair, reliable inter-device communication is essential for determining both appliances’ roles and current status. The RPC channel carries the HA state information, heartbeats, and configuration synchronization between the pair. If RPC nodes are configured incorrectly, the two appliances cannot exchange this critical state information. As a result, the secondary cannot confirm the primary’s status or its own role, so it shows a state of Unknown.

Disabling synchronization on the secondary would stop config updates from flowing, but the HA control channel could still provide status through RPC, so Unknown is not the default outcome. Blocking SSH (TCP port 22) doesn’t affect the HA state communication channel, and both devices being configured as primary would lead to a split-brain scenario rather than a simple Unknown state on the secondary.