[ntp:questions] Date Jumped

Richard B. Gilbert rgilbert88 at comcast.net
Wed Jan 13 12:33:14 UTC 2010


Rob wrote:
> Maynard <maynard7fold at gmail.com> wrote:
>> On 1/7/10, the date on our domain controller jumped to 12/7/10, and
>> was there for about 11 minutes before it reverted back to the current
>> date.  At the time this happened, our NTP server was pointed to
>> pool.ntp.org.  We also have a few Novell servers that were pointed to
>> the same IP addresses as our Server 2003 Domain Controller, and the
>> NTP server for our Novell network also jumped ahead.  Are we the only
>> ones that had this issue on this day?  Or are there others out there
>> that experienced the same problem on the 7th.  Thanks
> 
> This can happen any time.  pool.ntp.org is a large collection of
> servers that joined a voluntary pool of servers.  Any single server
> in this pool can send the wrong date and time if it likes to, or if
> there is an error.
<snip>
> It is better to use at least 3 different servers from the pool.  I.e.
> use servernames 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org for 3
> different servers.
> 
> That way, of one fails or plays nasty games, your time will not be
> affected.

Better still to use at least four servers, whether from the pool or not.
Using only three servers leaves you vulnerable; if one of them fails you 
are left with two and no possibility of "voting one out" if one the 
remaining servers fails, for it is written that a man with two clocks 
can never be certain what time it is!




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