Can you clarify what NTPSynchronized (extracted from DBUS) actually states?
When this contains “true”, Does it means NTP has synchronized at least once?
Or does it means the last NTP synchronization attempt was successful?
Under which circumstances this will contain “false”?
This is actually information from the Network Time Protocol (NTP) service running on the device and not something resin-specific. This indicates that the time has synced and a correction factor for the local clock has been computed, so the time should be reliable going forward. The only situation I am aware of under which this will be false is if the system is unable to connect to a network time server for some reason.
NTP does not rely on every attempt to sync being successful (in fact, it’s built to recognize when a server is lagging or is no longer available and correct for that) so this should not change if the most recent poll attempt was missed or failed.