If this optional flag is enabled, use only Status-Server requests (if any) to determine that the target server is failed when there is no reply. If this is not enabled, use no-reply to any type of request. This parameter uses NoreplyTimeout, MaxFailedRequests, and MaxFailedGraceTime during failure detection. This is not enabled by default.

FailureBackoffTime has no effect when UseStatusServerForFailureDetect is enabled. Once a Host has been marked as failed, it remains marked as failed until a reply is received from it (typically in response to a subsequent Status-Server request).

If you enable this, ensure that KeepaliveTimeout is set to a sensible interval to balance between detecting failures early and loading the target server.