[ntp:questions] The libntp resumee...

Kay Hayen kayhayen at gmx.de
Fri Sep 5 17:41:16 UTC 2008

Hello Richard,

you wrote:

> The "rules" about how often to query a daemon are not all that
> complicated.  The fact that there ARE rules is due to some history;
> google for "Netgear Wisconsin" for the sordid details.  For a "second
> opinion" google for "DLink PHK".

Fascinating reads indeed, thanks for the pointers. 

What worried me more was how often we can query the local ntpd before it will 
have an adverse effect. Meantime I somehow I sought to convince me I should 
be able to convince myself that ntpq requests are served at a different 
priority (other socket) than ntpd requests are. I didn't find 2 sockets 

> Briefly, you use the defaults for MINPOLL and MAXPOLL.  You may use the
> "iburst" keyword in a server statement for fast startup.  You may use
> the "burst" keyword ONLY with the permission of the the server's owner.
> 99.99% of NTP installations will work very well using these rules".  If
> yours does not, ask here for help!

Now speaking about our system, not the middleware, with connections as 

External NTPs <-> 2 entry hosts <-> 8 other hosts.

And iburst and minpoll=maxpoll=5 to improve the results.

Currently we observe that both entry hosts can both become restricted due to 
large offsets on other hosts, so they become restricted and that will make 
the software refuse to go on. Ideally that would not happen.

I will try to formulate questions:

When the other hosts synchronize to the entry hosts of our system, don't the 
other hosts ntpd know when and how much these entry hosts changed their time 
due to input? 

Would NTP would be more robust if we would configure routing on the entry 
hosts, so that they can all speak directly with the external NTPs on their 

Is the use of ntpdate before starting ntpd recommended and/or does the iburst 
option replace it?

Best regards,
Kay Hayen

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