TimeKeeper behavior on startup with seemingly invalid host time
TimeKeeper will check that the time on startup is not outside of a seemingly normal range. If the time is older than 30 years after the release of a given version of TimeKeeper or 5 years before then the system time will be set 5 years before the release date. This is to ensure proper startup of TimeKeeper when the time has been set to a wildly invalid time.
In some cases this means that on startup TimeKeeper will set the host time twice. First immediately on startup to make sure TimeKeeper can start correctly. Then once TimeKeeper has determined the correct time from a time source.
Incoming time validity checks
A similar check is applied to incoming time from all time source types. If the time is earlier than 5 years before or later than 30 years after the release of TimeKeeper the time sample will be rejected. This does mean that simulating time outside of what is considered reasonable time cannot be done. For information on how to do testing outside of these ranges please contact email@example.com.