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Pieter

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Reply with quote  #1 
Strange thing happened.
On 31the december around 14.00 (02.00 pm) our PDCe got a wrong time. It had the correct time, but was on the wrong date : 1/1/2017 insteda of 31/12/2016.
Our PDCe synchronizes with ntp1.belbon.be (Belgium).

Did any of you ever had the same problem ?
What do you use as extrenal NTP server ?


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wkasdo

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Reply with quote  #2 
Hi Pieter,

That domain does not exist. The time jump did probably come from that external NTP server, I agree.

My larger customers mostly use their own NTP servers syncing directly with the atomic clocks. Alternatively, use a managed time service from your ISP. If that is also not possible, consider to use one of the larger public NTP services. Not sure I'd care to recommend one, but avoid please avoid time.windows.com because that is strictly meant for consumers. I'd also avoid *navy.mil, see what happened in 2012 [smile]


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Pieter

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Reply with quote  #3 
Quote:
Originally Posted by wkasdo
That domain does not exist.

Typo, it should be: ntp1.belbone.be

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Pieter

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Reply with quote  #4 
Where can I find a list of atomic clocks, preferably in Belgium or at least Europe ?
Is their a reference ?

Somebody adviesed me to user CERN ntp server, but I can't find the FQDN.


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cj_berlin

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Reply with quote  #5 
Quote:
Originally Posted by Pieter
Where can I find a list of atomic clocks, preferably in Belgium or at least Europe ?


Hi,

what Willem is probably meaning is something like https://www.meinbergglobal.com/english/products/usb-dcf77-clock.htm so pulling time DIRECTLY from the clock providers.

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Pieter

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Reply with quote  #6 
OK, thanks for clarifying that.

And what about a public NTP server ?
Is their a list of reliable NTP servers for Belgium/europe ?

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Reply with quote  #7 
For reliable, I suppose you mean other than those listed on the "NTP Pool Project"?

They have a sort of disclaimer for that matter and recommend Meinberg (already mentioned above).

CERN NTP servers are listed in the script shown on this page but I'm not sure they are meant to be publicly accessible:

https://twiki.cern.ch/twiki/bin/view/LHCb/NTP

ip-time-1.cern.ch
ip-time-2.cern.ch


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wobble_wobble

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Reply with quote  #8 
This is the list I use
http://www.pool.ntp.org/zone/europe

I use the Irish points for 1 + 2 and a European one for three
As Willem mentioned larger customers have their own clocks, but they tend to hide them in my experience.




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Pieter

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Reply with quote  #9 

Thanks everybody for the replies. 
I see three options:
1. buying a atomic clock device (3000 to 4000€)

2. buying a DCF77 device (100 to 150€). Company is in Belgium, so that should work.
See https://www.meinbergglobal.com/english/products/usb-dcf77-clock.htm#Description and https://en.wikipedia.org/wiki/DCF77

3. Using a public NTP server. I'll go for pool.ntp.org

Does anybody have an idea how I can monitor if our time is correct ? Is there a tool to compare the time of our PDCe with another public NTP timesource




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wobble_wobble

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Reply with quote  #10 
No I don't know of a tool, but I've never gone to look for one.

On VMware I tend to set the hosts to the most local NTP Pool server, then set the PDC to that same source and allow AD to manage time from the PDCe to all other Windows devices.
In this case, you disable time sync with the guests from the hosts on VMware tools.
There are times I've seen this not work and there are config changes one can make to make sure time sync does not occur.

On a Hyper-V host its generally sync'd with a a DC for a resource forest if a big enough deployment, or I manually set the host to the most local NTP Pool.
Again, set the PDCe to the same local NTP.
Not seen as many issues with time skew on Hyper-V as on VMware.

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Pieter

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Reply with quote  #11 
Just a short summary of what I did.

1. used be.pool.ntp.org as NTP timesource on the PDCe

2. added registry keys HKLM\System\CCS\Services\W32Time\Config\MaxPosPhaseCorrection and MaxNegPhaseCorrection = 300 (decimal). This prevents that time will be synchronized if it is more than 5 minutes out of sync whith the NTP source.

3. wrote a script based on w32tm.exe /stripchart /computer: other_NTP_server  /samples:1 | find "*" . 
If errorlevel is 0, then * was found, meaning that time was not more than 10 seconds out of sync. 


FYI : I found this a very good article https://blogs.technet.microsoft.com/industry_insiders/2006/08/29/windows-time-and-the-w32tm-service/ written by Nathan Winters, who is also active on this forum. Thanks Nathan !



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