[ntp:questions] Time of by 4 min

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Fri Mar 14 04:09:37 UTC 2014

On 2014-03-13 11:48, greg.wayne.smith at gmail.com wrote:
> That's a pretty slick program just from looking at the page. I will play around with in and see. I tend to not install any 3rd party apps on my DC's though.
> I did mine the old fashion way by just setting the registry settings.
> Basically this for Windows servers: http://www.pool.ntp.org/en/use.html
> I have never had any issues till about 3 weeks ago.
> My server is not slowing losing time... It's a solid 4 min off for the past 3 weeks.

Site http://time.gov/HTML5/ agrees to within a second with
http://www.usno.navy.mil/USNO, http://tycho.usno.navy.mil/simpletime.html,
my WWVB watch and clock, my cell network time, and my NTP server; and
network backup servers are within single digit ms offsets.
The Weather Network on TV is delayed 6-7s.

Your college wifi, LAN, or upstream ISP may be running a proxy server
or your browser cache could be affecting the view - try hitting
<ctrl-F5> to force a proxy refresh in some browsers - in some browsers
you may have to clear your local browser cache to solve caching issues.
Try cross-checking against USNO or other time sites in separate windows.

In Windows, only Primary Domain Controller time is authoritative, and only
needs to keep domain members within 5 minutes for Kerberos authentication,
so if the upstream server is not synched from more frequently than MS
defaults of a few days, or the PDC's upstream server itself is not synced
regularly to decent sources, time could drift a few minutes.

Depending on setup, phones could be showing GPS, cell network, SNTP, or
time from a web page: you do not specify exactly what you are using as a
reference, and exactly what it is you are comparing against it: suspect
your reference!

A number of NTP servers appeared unavailable since NTP DDoS amplification
attacks earlier this year, and HNAP1 router attacks probably have not
helped lessen the load on downstream and ISP networking staffs, who may
be implementing mitigations without due consideration for side effects.

Take care. Thanks, Brian Inglis

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