[ntp:questions] NTP Server Answers at startup, then stops answering

Steve Kostecke kostecke at ntp.org
Thu Sep 20 19:20:41 UTC 2007


On 2007-09-19, Curt LeCaptain <lecaptainc at infinitytechnology.com> wrote:

This probably has nothing to do with the issue you discus in this
article, but the following configuration tweaks wouldn't hurt:

> server ntp1.cs.wisc.edu
> server ntp3.cs.wisc.edu
> server nss.nts.umn.edu
> server ntp1.chiccp.net

Append iburst to all of your server lines. Doing so will speed up ntpd's
initial sync from ~5 minutes to ~20 seconds.

iburst causes ntpd to send the first 8 packets to the remote time server
at 2 second intervals, instead of the default minimum of 64 seconds,
whenever that server becomes reachable. After the initial 8 packets ntpd
reverts to the normal poll times.

> restrict ntp1.cs.wisc.edu mask 255.255.255.255 nomodify notrap noquery
> restrict ntp3.cs.wisc.edu mask 255.255.255.255 nomodify notrap noquery
> restrict nss.nts.umn.edu mask 255.255.255.255 nomodify notrap noquery
> restrict ntp1.chiccp.net mask 255.255.255.255 nomodify notrap noquery
> restrict 192.168.1.0 mask 255.255.255.192
> restrict 192.168.1.64 mask 255.255.255.192
> restrict 127.0.0.1

You could greatly simply your restrictions as follows:

restrict default nomodify notrap noquery
restrict 127.0.0.1

If you need to allow authorized clients on one of your sub-nets to
query ntpd add the following as appropriate:

restrict aaa.bbb.ccc.ddd mask 255.255.255.eee notrap nomodify

More information about ntpd access restrictions is available at
http://support.ntp.org/Support/AccessRestrictions

> My problem is this: at startup, other servers are able to poll my NTP
> server. After about 5-10 minutes, they're no longer able to poll and
> fail their attempts from there on out, as if the service just stops
> answering. Any suggestions would be great, I'm really lost at this
> point.

Please let us see the output of ntpq -p from the server at the following
intervals after ntpd start up: 1 minute, 5 minutes, 10 minutes, 20
minutes.

-- 
Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/




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