I turns out that quote: “By default, the primary domain controller (PDC) emulator gets its time from the BIOS clock”. It means you will loose connection from AD clients to PDC when you will have large time skew (more than 1 hour if I remember correctly). To configure w32tm service do the following:
w32tm /config /manualpeerlist:time.windows.com /syncfromflags:MANUAL
w32tm /config /update
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