[ntp:questions] Re: simple time server

Richard B. Gilbert rgilbert88 at comcast.net
Sun Aug 6 02:49:47 UTC 2006

Danny Mayer wrote:

> Darren Dunham wrote:
>>Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>>>>By constrast, a Windows clock keeps local
>>>>time.  If you transport a Windows computer from Los Angeles to New
>>>>York, you normally tell the kernel to change its clock by 3 hours.  If
>>>>you transport a Unix system, you don't.  You just tell the various
>>>>programs that report the kernel's time that you'd like to see it in
>>>>EST now.
>>>Maybe YOU reset the Windows clock that way.  Windows does have the 
>>>facility to specify a time zone and at least some of us use that 
>>>facility to set the correct time zone for the zone we happen to be in.
>>I believe "specify a time zone" and "tell the kernel to change its
>>clock" are equivalent on Windows.  Yes?
> No. Windows uses UTC for internal timekeeping. Timezones are only for
> local display of time, just like Unix. Notice that you need to nothing
> to go between daylight savings time and local standard time in any
> timezone. VMS is the only operating system that I am aware of that uses
> local time for internal timekeeping, and that may have changed since I
> was involved with it. I don't know what IBM mainframes do.
VMS joined the modern era, timewise, back in the 1990's.  I believe that 
VMS V6.2-1 supported a UTC clock and local timezones.  The UCX TCP/IP 
stack (V4.0, I believe) supported a primitive (V3.x) ntpd.  The time 
change from standard to daylight and back is not automatic; you have to 
run a script at 2:00 AM on D-day.  If you're running a Database, you 
shut it down while this is going on.  Not sure if it's really necessary 
but I've always been told to do it that way.

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