[ntp:questions] iburst

Richard B. Gilbert rgilbert88 at comcast.net
Mon Nov 27 01:22:01 UTC 2006

terrypearl wrote:

> Added "iburst" to the server line in /etc/ntp.conf as:
> server 0.north-america.pool.ntp.org iburst
> server 1.north-america.pool.ntp.org iburst
> server 2.north-america.pool.ntp.org iburst
> I understood that adding the 'iburst' would spee synch on boot.
> Unfortunately, it hasn't. It still takes anywhere from 3 to 5 minutes to 
> synch.
> Is there a way to reduce the synch time to seconds instead of minutes??

Not really.  Even with iburst it takes something like twenty seconds to 
collect the information necessaray to START synchronizing the clock. 
The maximum slew rate of 500 parts per million means that it takes a 
while to correct any error.  I think that your "3 to 5 minutes" applies 
to a "warm start"; e.g. starting with a good drift file.  A cold start 
takes something like thirty minutes to get tight synchronization.

This is all relative.  If you start ntpd with -q and use iburst you will 
probably not be off by more than 100 milliseconds.

If you need to be in tight synchronization at all times, don't ever shut 
down!!!  If your O/S requires frequent reboots, change to a better one.

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