[ntp:questions] different Ntp servers...

Richard B. Gilbert rgilbert88 at comcast.net
Mon May 25 14:56:18 UTC 2009

Towli wrote:
> Hi all
> Our servergroup is synchronizing their Domain Controller's-Ntp towards a 
> public stratum 2 ntp-server from the dk pool.
> We, in the network dept., synch our core switches to our 2 own internal 
> stratum1 DCF77 time boxes (and a public for backup) and therefrom to all 
> our Networking equipment
> Is this a potential risk og doesnt it matter? I mean - i take the time 
> is supposed be the same no matter where you ask, (with a little offset 
> adjustment).
> ?
> Best rgds
> /Towli

The various countries have their various standards authorities 
responsible for maintaining the official clock!  These authorities 
synchronize their clocks to within a few nanoseconds.  (Remember that 
these agencies and clocks are supported by governments that can afford 
the necessary technology.)

You will get the same time no matter which standards authority's clock 
you ask.  The error/uncertainty in the time you get is due to the 
difficulty in measuring the transit time from the official clock to you.

If you need extreme accuracy, you can install a GPS timing receiver, 
spend about a month doing a "site survey" to determine your location to 
within plus/minus a foot or two and be certain of the time within a 
nanosecond or two.

Radio astronomers, for example, really care about nanosecond accuracy. 
Most people have requirements far less stringent!

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