The change from standard time to DST is not much of an issue since you jump one hour forward.

Example:

The clock jumps forward from 02:00 standard time to 03:00 DST, and the day has 23 hours. In that case, there is no data between 02:00 and 03:00 in the morning since that hour, for that day, did not exist.

When you switch from DST to standard time in the fall, you jump one hour back.

Example:

The clock jumps backward from 02:00 DST to 01:00 standard time, repeating that hour, and the day has 25 hours. You reach 01:59:59, then immediately revert to 01:00:00. If the system did not react, it would essentially re-record that hour, so the first instance of 01:30 would be overwritten by the second instance of 01:30.

To prevent such an issue from happening, your system archives the current video in the event the system time changes by more than five minutes. You cannot view the first instance of the 01:00 hour directly in any clients, but the data is recorded and safe. You can browse this video in XProtect Smart Client by opening the archived database directly.