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

David Woolley david at ex.djwhome.demon.invalid
Thu Jan 23 08:25:16 UTC 2014


On 23/01/14 07:29, ardi wrote:

>
> Why should i need the restrict line xx.xx.xx.xx?
> What does the first restrict line means?

You don't.
See the documentation.  Sets a fairly safe environment in which you can 
be used as a server, but not much else, by the general public.

>
> b1)In case using 2 ntp-servers from which my ntp-client can get time,
> is my ntp-client taking time from xx.xx.xx.xx
> and if this server is not reachable then from xx.xx.xx.yy?

No.  It is using a weighted average of both.

>
> What happens if xx.xx.xx.xx comes up again?
> Does client take time again from the xx.xx.xx.xx?

It starts using both again.
>
> b2)
> What does prefer do in this case b2)?
> Is there any difference between b1) and b2) case?
>

Never investigated prefer in detail.
>
> b3)
> what about this case b3) below?
> Is time taken for the ntp-client according to order of lines - i mean the xx.xx.xx.xx is taken as time source?
> or the 2nd server xx.xx.xx.yy is preferred?

See b1.  The only time the order of servers may have an effect is if you 
exceed the maximum number, and I'm not sure of that case.  Otherwise 
time quality metrics determine the weighting of the contribution of each 
server and which one is the figurehead system peer (there is also some 
hysteresis to avoid system peers changing too often).  I am pretty sure 
that the effect of the order is not specified.



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