[ntp:questions] Time of by 4 min

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Thu Mar 13 22:00:39 UTC 2014


greg.wayne.smith at gmail.com wrote:
> My Windows 2008 server pulls from us.pool.ntp.org and it's off by 4 min compared to time.gov.

If you are using _only_ pool.ntp.org servers,
 I hope you are using the pool directive,
  or at least four server detectives. e.g.

restrict source
pool us.pool.ntp.org iburst preempt
 or
restrict source
server 0.us.pool.ntp.org iburst preempt
server 1.us.pool.ntp.org iburst preempt
server 2.us.pool.ntp.org iburst preempt
server 3.us.pool.ntp.org iburst preempt


Have you added e.g.:
 server time.nist.gov iburst noselect

to your NTP servers, so you can get a real offset?
Then check your server with e.g.
 ntpq -n -c "lpe" -c "las" -c "rv 0"


> It's just the time is off by 4 min compared to our cell phone providers.
>  Sprint, ATT, T-mobile. And thus the students are in an uproar.

ATT uses its own NTP servers, 12.230.208.### & 12.230.209.###,
 e.g. Some used by ATT cell phones, micro WAPs, ...
# server 12.230.208.48 iburst
# server 12.230.208.133 iburst
# server 12.230.209.5 iburst
# server 12.230.209.133 iburst

 I'm certain other carriers do the same,
  Apple has their own for their cell phones, ipads, ...


Re: If your students are referencing http://time.gov/ , see http://time.gov/aboutB.html
<BlockQuote>
Issues
 This web site is intended as a time-of-day service only.
  It should not be used to measure frequency or time interval,
   nor should it be used to establish traceability to NIST or the USNO.
</BlockQuote>

I think the http://time.gov/ Graphics time if likely to be within seconds,
 much less minutes.


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