Unknown alerts may occur in the following cases.

• Expression monitoring
  • When a metric value cannot be obtained by expression
  • When obtaining a metric value by expression times out
• Check monitoring
  • When the specified command (plugin) has an exit status other than 0, 1, or 2
  • When the specified command (plugin) times out

These alerts indicate that monitoring is not being performed as intended and for this reason, it is not possible to prevent them from being issued. We recommend that you investigate and resolve the cause of the Unknown status and also check the status of the monitoring target.