All panic has ensued at our work over this leap Second time and we have been calling Microsoft and all vendors to get clarity, In essence tomorrow Tuesday the 30th of June we gain 61 seconds in a minute. Now for an IT system to work perfectly time source is critical but this extra second over weeks and months can lead to a few minute time drift. Please see this Microsoft Blog post for further reassurance around the leap second change: Another look at the impact of the coming 2015 leap second on Microsoft products (not much) - Satisfy Me - Site Home - MSDN Blogs Simply, Microsoft Operating systems are not designed as mission critical time keeping systems and are allowed to be several seconds out of sync at any time. I cannot see any reason why the leap second will affect anything, but increased awareness should be given as nothing is 100% guaranteed in the complex environments we or anyone else supports. More on this A leap second will be added to time next week but watch out - chaos may ensue - Science - News - The Independent @DeviateDefiant our NTP source all ok for server mate?