What time does an Atomic Clock reset itself for Daylights Savings?

Question

I am curious of what time an atomic clock will reset itself for Daylight Savings. This is from last April, 2008. I was under the belief it was predetermined at 3:00a.m.

This is in the state of Kansas, and on the CST (-6) time zone.

Answer 1

They don't. UTC (coordinated universal time) just advances forward at one second per second. It never jumps forward or back an hour. The time zones themselves change their offset from UTC, so CST is -5, while CDT is -6.

The official clocks do occasionally add leap seconds at the end of a day (23:59:60) to account for the gradual slowing of the rotation of the earth.