[ntp:questions] Re: NTP Configuration for DST?

Danny Mayer mayer at ntp.isc.org
Fri Jun 16 11:21:34 UTC 2006


Richard B. Gilbert wrote:
> Kluth, Richard SEA wrote:
> 
>> I am not familiar with the
>> configuration options of NTP, but I am wondering if there is a way to
>> configure the NTP server to respond to the client query (my device) with
>> its locally adjusted time and not the UTC time?
>>
>> I can adjust my device time via programming code, but it would get
>> overwritten via the next NTP update, so I would continually be running
>> the code in a vicious loop.  If NTP does not have a configuration
>> option, is there anything else you can suggest?
>>
> 
> As you note, NTP deals only with UTC.  There is no provision in the code
> for dealing with time zones or or standard vs. daylight time and I would
> be extremely surprised if anyone on the development team would be
> willing to add such a thing.
> 

I would put it much stronger than that. This would go against the whole
architecture of NTP. Timezone information including Daylight Savings
Time is a local phenomenon. That's what a GUI or even a command line
would display to the user. To change this would violate the NTP protocol
and cause massive dislocation of reliable time distribution. Think
locally. Your clients get the NTP packets and turn them into local time.

> You can either add the capability to handle daylight time to your
> devices or require the customer to change his time zone twice each year
> in order to handle the time shift.

You haven't said what time is needed to be displayed where. If you are
displaying the time of your local device remotely, have the remote node
deal with the time zone.

> 
> Handling daylight time can be a nightmare; Congress, and state
> legislatures tinker constantly with the rules.  Legislatures in
> countries other than the US have the same tendency and some practice
> even less restraint!!

That can easily be handled by a timezone file which is what most O/S's
use the days. You shouldn't need to update more than twice a year or
however many times your local legislators change their minds...

Danny



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