False positives have been fixed in the rare cases of PINGing to a disconnected host with a response time exactly matching the timeout, which led to a very rare chance of returning success when the host is actually Down.
Monitors do not issue corresponding alerts when they are created in Down or Warning state.
The Default Down State Timeout has been changed from 10 to 20 seconds for all monitors. A default Warning State Time Limit of 10 seconds is introduced. Both thresholds have the spike filtering enabled to ignore a single threshold violation.
The PING monitors now use different thresholds: 5 seconds for Down and 0.5 seconds for Warning (with spike filtering enabled). Polling interval for PING monitors is now 30 seconds.
You can find more about the release in Release Notes.