I use multiple virtual boxes for development and correct time and date is important for me when I push git commits. I do not shut down my host - it runs for months without restarting. I only hibernate it for nights and weekends. This introduces weird issue to my guest operating systems (all debians from turnkeylinux.org) - after some time, the date of guest operating systems is off by few days.
Although all guests use NTP it does not work if it detects that date is off by some large values (few hours seems to be enough). Is there any way to force NTP sync even for large time differences? Or any other solution that would restore correct date and time on guest boxes after host resumes from hibernation?