I just turn on my computer .. and it tells me .. because that time is changed automatically.
Easy.
I had to get out of bed at 0100 this morning and drive to work. Had to IPL an IBM Z10 series mainframe to change the time to DST. This takes about 30 minutes using over 100 keyboard commands to make sure the network, servers and company web sight are all set up correctly.
I got paid good for my time.