[ntp:questions] The libntp resumee...

Richard B. Gilbert rgilbert88 at comcast.net
Fri Sep 5 12:17:46 UTC 2008


Kay Hayen wrote:
> Hello,
> 
> thanks to all who replied. Unfortunately the moderation bit made all of my 
> last replies expire and instead of reposting them, I choose to sum things up 
> in a single post.
<snip>
> 5. The NTP rules about how often to query a daemon. I have tried to read up 
> about it, but only found general advice. Under the assumption that ntpd is 
> not multithreaded querying it at the time it should respond to other servers 
> is slightly unfortunate. I was thinking that the query is so fast that it 
> doesn't matter. I will have to back it up with numbers. I presume we could 
> query the local ntpd for its time in a loop and compare with local current 
> time to get an idea if extra libntpq queries degrade it or not.
> 

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".

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!

"burst" is intended for systems that make a dialup telephone connection 
to a server three or four times a day.

"iburst" sends an initial burst of eight request packets at intervals of 
two seconds.  Thereafter, the server is polled at intervals between 64 
and 1024 seconds; ntpd adjusts the poll interval within this range as 
needed.




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