[ntp:questions] simple nt.conf cases for ntp-client

Marco Marongiu brontolinux at gmail.com
Thu Jan 23 16:12:16 UTC 2014

On 01/23/2014 04:16 PM, Brian Utterback wrote:
> On 1/23/2014 8:06 AM, Marco Marongiu wrote:
>> If you have just two references, the step 2) doesn't bring you anywhere
>> as it is impossible to reach a majority. It's like you're skipping step
>> 2), and the results lose accuracy.
> Not to put too fine a point on it, but if you have two servers and one
> of them has the correct time and one is way off, with only two servers
> the one that is far off is just as likely to be chosen as the correct
> one. Worse still is you are subject to "clock hopping", where each of
> the two servers are chosen alternately. Most news versions of NTP have a
> certain amount of server "stickiness" built in to suppress clock
> hopping, but it can still occur, especially if your servers reboot
> frequently. Clock hopping can destabilize the frequency correction
> feedback loop which in turn can lead to increasingly large clock
> offsets. Not what you want.

Thanks for pointing out this Brian, it was not a detail. And it's often
referred to with the sentence "a man with two clocks never knows what
the time is" (or a similar sentence in correct English :)

-- M

More information about the questions mailing list