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

Steve Kostecke kostecke at ntp.org
Thu Oct 28 12:00:40 UTC 2010

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/

More information about the questions mailing list