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

Brian Utterback brian.utterback at oracle.com
Thu Jan 23 15:16:41 UTC 2014


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.

Brian Utterback


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