We are receiving too many number of alerts in Zabbix frontend coming from 2 host in the monitoring . The alert indicating that the servers has been rebooted. As per checking, the alert has been automatically resolved 3 to 5 mins after the alert stating that it has been restarted.

Upon checking with the host owner that we monitor, there are no changes on the servers. Also noticed an alert indicating that the drive F disk space is full but upon checking the server does not have any Drive F on it. 

We run some troubleshooting with the team of the host owner and do the following steps but still we are getting false positive alerts that the servers has been restarted.

1. Uninstall the Zabbix agent and any related folder from the server. 
2. Remove the server/host from the Zabbix frontend. 
3. Reinstall the Zabbix agent. 
4. Reconfigure the host from the Zabbix frontend. 

This is the system uptime that we've seen on the previous monitoring that there were inconsistency. 

We are just getting these alerts from 2 out of 302 that we are monitoring. 

 The version of the zabbix that we used is Zabbix 3.4.1.