[time] 8 hour jump in time

ntpadmin at oc9.com ntpadmin
Mon Dec 4 15:32:20 UTC 2006


On Mon, 4 Dec 2006, Claypole, David wrote:

> THIS MESSAGE IS SUBJECT TO THE CONFIDENTIALITY NOTICE AT THE END OF THIS COMMUNICATION
>
>
> Thanks Louis
>
> I am using a windows client but only have uk.pool.ntp.org as a source, I
> then sync my domain with this client.
>
> If I use ( net time /setsntp:"0.uk.pool.ntp.org 1.uk.pool.ntp.org
> 2.uk.pool.ntp.org" ) does that mean it will check 3 servers before
> adjusting ? I presume the 3 servers would have to be with a certain
> threshold of each other before the Server changed its time. So if one
> was 8 hours out then it wouldn't happen.
>
I have several ntpd server so let me try something to find out the answer 
to your question :

C:\Documents and Settings\HP_Administrator>net stop w32time

C:\Documents and Settings\HP_Administrator>net time 
/setsntp:"192.168.11.11 192.168.11.9 192.168.11.8"

C:\Documents and Settings\HP_Administrator>net start w32time

Well, I think you might be safe with this setting because I now see the 
Windows XP machine connecting to all 3 ntpd servers everytime it polls for 
time. To be 100% sure, we would have to know what w32time does when one of 
the server has a huge 8 hours offset... It should obviously react 
properly. Let's just hope w32time doesn't do an average of the 3 results 
it gets... ;-)))

Anyway you seems to be much safer with /setsntp:"0.uk.pool.ntp.org 
1.uk.pool.ntp.org 2.uk.pool.ntp.org" so I would just leave it like 
that for now. If w32time is smart enough to handle bad servers, you 
should be fine.

See Microsoft documentation at:
http://technet2.microsoft.com/WindowsServer/en/library/71e76587-28f4-4272-a3d7-7f44ca50c0181033.mspx?mfr=true

Don't forget to stop/start w32time although, I beleive it is needed for 
the new sntp configuration to be taken into account.

> I quess the server I checked on Saturday @ 9:30 was out.
>
> Thanks
> David Claypole
>
>
> -----Original Message-----
> From: ntpadmin at oc9.com [mailto:ntpadmin at oc9.com]
> Sent: 04 December 2006 13:54
> To: Claypole, David
> Cc: timekeepers at fortytwo.ch
> Subject: Re: [time] 8 hour jump in time
>
> On Mon, 4 Dec 2006, Claypole, David wrote:
>
>> THIS MESSAGE IS SUBJECT TO THE CONFIDENTIALITY NOTICE AT THE END OF
>> THIS COMMUNICATION
>>
>>
>> Have been using the uk.pool.ntp.org service for some time now without
>> any issues and its been great. On saturday  at 09:30 our server sync'd
>
>> and jumped by 8 hours causing us a few issues. Just windering if
>> anyone else had issues and if there is anything i can do to ensure it
>> doesnt happen again.
>>
>>
>> Thanks
>>
>> David Claypole
>>
>>
>
> Hi David,
>
> Are running ntpd ? If not I would recommend it.
>
> Basically, if you aren't running ntpd, you must be using some kind of
> sntp client ( e.g. ntpdate on linux, w32time on windows).
>
> The sntp clients ( s is for simple) take their time from the first
> available server as far as I can tell. This raise the risk of what
> happend to you happening again. Any given server may go wrong (any clock
> device also), not only servers from the pool.
>
> When you run ntpd you usually specify 3 or more time source servers to
> connect to :
>
> 0.uk.pool.ntp.org
> 1.uk.pool.ntp.org
> 2.uk.pool.ntp.org
>
> ntpd is smart enough to detect if one of the 3 servers go wrong and ntpd
> will continue to provide you with reliable time unless all servers go
> wrong.
>
> If you do not run ntpd, consider setting at least 1 ntpd server for your
> network and have your local machines read time from your own ntpd
> server.
> It is OK to use sntp client on your internal network because you can now
> trust your own ntpd server to give the right time.
>
> If you are already running ntpd with multiple servers as source of time,
> then something more serious did occur beacuse all the time source
> servers would have to fail in order for an 8 hour glitch to occur.
>
> Louis
>
>
>
>
> * * * * * * * * * * * * * * * * * * * * * * * * * *
> This e-mail is private and may be confidential and is for the intended recipient only. If misdirected, please notify us by telephone and confirm that it has been deleted from your system and any copies destroyed. If you are not the intended recipient you are strictly prohibited from using, printing, copying, distributing or disseminating this e-mail or any information contained in it.
> * * * * * * * * * * * * * * * * * * * * * * * * * *
> We use reasonable endeavours to virus scan all E-mails leaving the firm but no warranty is given that this E-mail and any attachments are virus free. You should undertake your own virus checking. The right to monitor E-mail communications through our networks is reserved by us.
> * * * * * * * * * * * * * * * * * * * * * * * * * *
>
> This message has been scanned for viruses by BlackSpider MailControl - www.blackspider.com
>

Louis



More information about the pool mailing list