[ntp:questions] Can or should the NTP protocol eventually serve timezone data?

Rob nomail at example.com
Fri Jun 19 11:43:31 UTC 2009


Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
> Rob wrote:
>> Hal Murray <hal-usenet at ip-64-139-1-69.sjc.megapath.net> wrote:
>>> In article <slrnh3k09c.1s1j.nomail at xs7.xs4all.nl>,
>>>  Rob <nomail at example.com> writes:
>>>
>>>> So your standpoint is that every system builder who wants to do
>>>> such localization should be on their own, providing their own update
>>>> mechanism, and there should not be a universal update mechanism for
>>>> timezone updates that is neutral to operating system?
>>> Why have a special update mechanism for time zone data?  Why
>>> not piggy back on updating everything else?  Isn't that the
>>> way it works now for most people?
>> 
>> Because time zone data can be useful for many more systems and
>> devices than are normally updated by some update service from an
>> OS vendor.
>> 
>> An NTP synchronized wall clock may not be loading fixes from
>> Windows Update, but it needs uptodate timezone information.
>
> Which the owner supplies!  I have two of these gadgets.  One is
> a RadioShack  product, the other is a La Crosse Technology WS-8001U
> "Radio Controlled Moon Phase Clock".  It's not "NTP Synchronized".  It's 
> WWVB synchronized; it receives the WWVB signals in the wee hours of the 
> morning when signal reception is good.  It does not provide microsecond 
> accuracy but it's certainly good to within plus/minus one second; 
> sufficient and even "overkill" for a household clock.
>
> Both of these gadgets allow me to set the time zone; all else is taken 
> care of by miracles of modern technology!

With a WWVB clock you don't need DST info because the transmitter
provides it.  When you have a NTP clock you don't get any info at
all about DST and you have to calculate it locally.  This requires
either manual action or automatic download of a file that provides
uptodate DST info for a zone whose name is configured one time.

For the US there is no practical difference as the DST rules do not
often change.  In some other countries there are frequent changes.

My house is full of radio clocks.  They work OK because the country
where the signals are transmitted and the country where I live are
in the same timezone, and both countries tend to use the same DST
rules under EU coordination.
However, should the government decide that we should use the local
time that is appropriate for our longitude (instead of the same time
as our neighbors), all my clocks would be off by one hour.
(these clocks are produced for the local market and have no timezone
setting)

These days of the year, sunset is after 10PM here.




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