[ntp:questions] Using ntpdate -b SERVER shortly after SERVER boots

Donald Murray, P.Eng. donaldm314 at gmail.com
Mon Feb 12 13:59:04 UTC 2007


On 10 Feb 2007 02:16:02 GMT, Steve Kostecke <kostecke at ntp.isc.org> wrote:
> On 2007-02-08, Donald Murray, P.Eng. <donaldm314 at gmail.com> wrote:
>
> > How quickly can an isolated ntp server respond to 'ntpdate' queries
> > after the server starts?
*SNIP*
>
> Changing the clock while ntpd is running is not a good idea. ntpd will
> attempt to "correct" the observed change in the clock.
>
> ntpd should be stopped, the clock adjusted, and then ntpd can be
> started.

Yes, that's how we adjust the time.

> You should append 'iburst' to the 'server 10.0.0.2' line. This causes
> the first 8 polls to SERVER to be sent at 2 second intervals and will
> allow the CLIENT to sync to SERVER in ~ 20 seconds.

Done.

> > Is there anything I can do to SERVER's ntp config to encourage it to
> > respond to remote ntpdate queries more quickly on startup?
>
> As I understand it, there is no configuration setting to do what you
> want. You would have to modify ntpd.

My revised plan is to initialize CLIENT's clock to SERVER as follows when the
ppp link comes up. While ntpd is stopped:
- attempt 'ntpdate -b SERVER'
- if ntpdate fails, use a CGI to obtain the current date on SERVER;
feed that to /bin/date

I bet this sounds pretty awful to most of you. It sounds kind of awful
to me as well.

Thanks for your suggestions. I appreciate everyone taking the time to respond.
Do I get a prize for most inappropriate use of ntp?  ;-)



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