This issue can occur due to the following conditions:
1. SNMP monitoring service is hanging or stopped
2. CPU utilization is extremely high
If the issue is cause by condition #1, then you will see the alerts at regular intervals. Whereas, if the issue is due to condition #2, you will see the alerts intermittently.
The monitoring service checks the status of hardware components periodically using internal SNMP queries. When the hardware monitoring service can not complete the monitoring task due to one or more of the above conditions, it returns an "Unknown" status and triggers the alert, if configured.
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