[LEAPSECS] Google, Amazon, now Microsoft

Poul-Henning Kamp phk at phk.freebsd.dk
Sun May 31 15:33:42 EDT 2015

In message <556B5D76.6000202 at edlmax.com>, Brooks Harris writes:

>> Most Windows boxes don't run NTP.
>I don't think that's true. As far as I know, Windows, either personal or 
>Server versions, synchronize using NTP, and did so with SNTP until Win 
>2000, then NTPV3, then NTPV4. I glean this from accumulated knowledge - 
>its difficult to find authoritative information from Microsoft about it.

So that depends what you mean by "NTP".

If you mean that your packets look like NTP packets, then yes, it does
run NTP.

But I mean "use the NTP clock model".

>On my personal laptop running Win 7, I don't have Active Directory, and 
>the W32Time service is *not* started. But it will synchronize via the 
>usual desktop "Internet Time" mechanisms. It uses either 
>"time.nist.gov", "time.windows.com", etc. These are NTP servers.

But what happens when the leap-second hits ?

Most likely, at some random time after the leapsecond, your clock
steps a second.

>Windows of any version is fundamentally following NTP.

Not even close.

That's why Meinberg still maintains their NTPD client.

You should find Martins presentation from FOSDEM about this.

>But that doesn't answer the first question about how the Leap Second is 
>applied to local time by Azure and/or Windows.

Because that is the only sane thing for them to do, given the (broken)
timekeeping in the software they run.

The fundamental question about leapseconds is not about where Rob can
find the sun at noon, but about teaching an awful lot of rather crap
programmers how to cope with a infrequent and intractable complexity
on short notice.

It seems like Daniels scheduling on this one may show us which is more

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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