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

ardi peter.knezel at gmail.com
Thu Jan 23 11:52:27 UTC 2014


On Thursday, January 23, 2014 12:21:15 PM UTC+1, Marco Marongiu wrote:
> On 01/23/2014 11:00 AM, ardi wrote:
> 
> > On Thursday, January 23, 2014 9:36:35 AM UTC+1, Marco Marongiu wrote:> Well, I have come across almost all of the pages, you are mentioning below,
> 
> > but it seems, i have "combined" the info wrongly for my example...:-)
> 
> 
> 
> :-)
> 
> 
> 
> 
> 
> > Does it mean these minpoll, maxpoll parameters are not needed in most
> 
> > of the cases?
> 
> 
> 
> Yes, that's what I mean.
> 
> 
> 
> 
> 
> > According to book Expert Network Time Protocol from PETER RYBACZYK:
> 
> 
> 
> I don't have that book. I'd appreciate that anyone in this list that has
> 
> reviewed the book can give their opinion about it.
> 
> 
> 
> 
> 
> > "The minpoll and maxpoll parameters represent minimum and maximum
> 
> > polling intervals for reference clock messages in seconds to the
> 
> > power of 2. For example, if minpoll=3 and maxpoll=4, the minimum
> 
> > polling interval would be 8 seconds, and the maximum polling interval
> 
> > would be 16 seconds."
> 
> > 
> 
> > What does "minimum and maximum polling intervals for reference clock
> 
> > messages" mean?
> 
> > polling = messaging with NTP servers to estimate the offset ???
> 
> 
> 
> Yes, but you don't need to query the servers every 16 seconds. Normally,
> 
> once a peer is selected, ntpd gradually extends the polling interval
> 
> from 64 to 128 seconds, to 256, 512, and finally 1024. Querying every 16
> 
> seconds is a bit obsessive and doesn't bring much more accuracy than the
> 
> standard settings. Not to mention that your references may rate limit
> 
> you, or refuse to talk to you altogether.
> 
> 
> 
> 
> 
> >> First: don't use two servers, it's the worst possible configuration.
> 
> > 
> 
> > Why not? what if one of the servers fail? then the client can get time from the other ntp-server.
> 
> 
> 
> Please, read this section and my previous message carefully:
> 
> http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO
> 
> 
> 
> I am not saying that you should use only one server: I am saying that
> 
> using two is bad, and that you should use four.
> 
> 
> 
> Ciao
> 
> -- bronto


Reading: http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO

Two time sources cannot be split into two parties where one has a majority.
What does this majority means?

Peter



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