[ntp:questions] systems won't synchronize no matter what

Parvin, Richard richard.parvin at hp.com
Thu Oct 28 14:43:37 UTC 2010

Thank you all.  Richard

-----Original Message-----
From: questions-bounces+richard.parvin=eds.com at lists.ntp.org [mailto:questions-bounces+richard.parvin=eds.com at lists.ntp.org] On Behalf Of Steve Kostecke
Sent: Thursday, October 28, 2010 7:01 AM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] systems won't synchronize no matter what

On 2010-10-28, Parvin, Richard <richard.parvin at hp.com> wrote:

> I've noticed that a lot of people use iburst on thier server lines.
> I'm wondering why.

iburst == initial burst

iburst causes ntpd to use a volley of 8 polls at 2 second intervals when
a time server becomes reachable (e.g. at start up). 

ntpd needs to poll a remote time server a minimum of 4 times to collect
enough data to choose it as the sys_peer (i.e. sync to it). The first
poll occurs after ntpd initializes and resolves the server hostname.

For this discussion we will assume the first poll takes place 5 seconds
after ntpd is started.

The default minimum poll interval (minpoll) is 64 seconds. Without
iburst ntpd needs at least 5+(3*64) or 197 seconds (3m17s) for initial

With iburst ntpd needs at least 5+(3*2) or 11 seconds for initial sync.

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

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