[LEAPSECS] Google, Amazon, now Microsoft

Tom Van Baak tvb at LeapSecond.com
Sun May 31 19:23:46 EDT 2015


Hi Brooks,

I don't know enough about Windows timekeeping in general or versions of Windows in particular to give you any authoritative answer. But here's one data point that might help clarify what you and PHK are talking about.

On Windows XP, click on the clock icon and look at the "Internet Time" tab. It says my laptop will sync against "time.nist.gov" (choice of nist or microsoft) automatically once a week (no choice). You can also manually initiate a sync.

I looked at the LAN packets during the weekly sync and it consists of a single NTP packet going out and a single reply coming back. See attached snapshot.

So, yes, Windows uses an NTP packet. But, no, it doesn't "run NTP".

Multiply this by 250 million [1] PC's still happily running XP and you can better understand why Microsoft hasn't been that interested in leap seconds, NTP, or participating in the hh:59:60 timestamp nightmare. It would make sense, like Google and Amazon, that their in-house data centers would want to more precisely and deterministically handle leap seconds. But note all three companies have decided to jump or smear time instead of creating a true leap second.

/tvb

[1] https://redmondmag.com/articles/2015/04/08/windows-xp-usage.aspx
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