Question

We currently have about 150 http and https monitors set up in our environment.  Several will occasionally go into unknown status for a poll or two then come back to up without any error or any apparent isssue with the url.  What are potential causes for a url monitor to go into unknown status?

aLTeReGo · Accepted Answer

There are several potential reasons, but they all tend to be extremely rare, so it's best that you enable debug logging on the assigned application monitor/s that are most likely to fail for seemingly no apparent reason. Then collect a diagnostic and open a case with support if any of HTTP components in these application templates report a false down status.

Some reasons that can cause a false down status of an HTTP/HTTPS User Experience Monitor could be issues with load balancers, high network latency, polling too frequently, timeout values too low, overloaded poller, network packet loss, IDS/IPS systems, and even Antivirus software. These are all extremely rare, so I'm not saying any of these are likely causes for why your HTTP/HTTPS User Experience Monitors are failing in your environment.  Your best bet is to gather debug logs for those monitored applications and work with support to diagnose the root cause of the issue.