Hello all !!
I want to know what is the meaning of the Unknown status
Unknown is just that. SolarWinds doesn't know what the status of that application is at the time polled. That could be because the underlying polling technology was failing, login failures (maybe issue with agent etc.), maybe an undefined dependency went down and it couldn't poll it, or the most likely is it timed out when polling its status. Surely there's more reasons but those are a couple reasons perhaps.