[ntp:questions] Re: NTP configuration problem
Richard B. Gilbert
rgilbert88 at comcast.net
Wed Feb 15 13:30:35 UTC 2006
J S wrote:
> I am trying to configure NTP client on a machine but observing
> unusual log.
> my ntp.config files read this
> driftfile /etc/ntp/drift
> restrict ntp1.cs.wisc.edu nomodify ntrap noquery
> server ntp1.cs.wisc.edu minpoll 4 maxpoll 4
> My drift file reads 0.000
> whereas tcpdump is unable to capture any packets
Lose the restrict statement!
Also, you should not specify minpoll and maxpoll without very good
reason! The defaults were carefully selected and apply to, perhaps, 99%
of all installations. By specifying the values you did, you load the
server unnecessarily and practically guarantee poor timekeeping
performance on your client.
The University of Wisconsin has very good reason to object to such usage
of their server! See http://www.cs.wisc.edu/~plonka/netgear-sntp/
Netgear was very fortunate to avoid a lawsuit and many operators of NTP
servers probably wish that U-Wisconsin had sued Netgear for every dime
they had; the example would have done a lot to prevent current problems.
If you MUST use restrict statements, specify the numeric IP address and
an appropriate value for the net mask. Using the domain name in a
restrict statement is not supported.
Finally, it' a generally a good idea to add "iburst" to the server
statement. This gets ntpd initialized in about twenty seconds vs. five
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