If the trigger time for a particular scheduled task run happens to fall during the transition time between daylight saving time (DST) and standard time (ST), the interval for that run will be different than expected.
Time zones that honor DST have a period of time that occurs twice during the transition from DST to ST. For example, in the US when changing from DST to ST, this hour occurs once while the DST is still in effect and again after switching to the Standard Time. The transition period occurs at 2 a.m., therefore 1:00:00 a.m. - 1:59:59 a.m. occurs twice (1:00:00 a.m. PDT - 1:59:59 a.m. PDT and 1:00:00 a.m. PST - 1:59:59 a.m. PST), where 1:00 a.m. PST is 60 minutes after 1:00 a.m. PDT. In this example, if the scheduled task is due to trigger any time between 1:00:00 a.m. - 1:59:59 a.m., the interval for that particular run of the scheduled task will not be as expected.
Similarly, when the time changes from ST to DST, the 1:00:00 a.m. - 1:59:59 a.m. hour does not occur at all. The local time changes directly from 1:00 a.m. to 2:00 a.m. So, if your scheduled task run was scheduled to trigger between 1:00:00 a.m. - 1:59:59 a.m., the interval for that particular run will be off by an hour.
The interval calculation for subsequent scheduled runs do not get affected.
Currently, there are four time zones that are not supported in ESM:
Kwajalein
Pacific/Kwajalein
Pacific/Enderbury
Pacific/Kiribati
These time zones fall in two countries, Marshall Islands and Kiribati.