[This host is stale, no data has been received within the last 1.5 check periods]
Yep, this is a message you can see inside checkmk. What do you like to know or want to ask about?
I want to know why we are in this state and what causes it
This can be caused by several things. A bit more input about your configuration, your version, your system infrastratucture would be nice.
Please also take a look into the official documentation to understand the state concept:
How do you fix the stale state of the host/service? Where is the check cycle set?
Making the host send it’s check results properly again.
At the rules under Host & Service Parameters -> Monitoring Configuration -> Service Checks -> Normal check interval for service checks
What caused the disk space to run out when I rediscovered the service on the host
How do I get the host to send the check results correctly again