CentOS - Apr 2010 - how long NTP sync to time server on CENTOS 4.X????

We have several CENTOS 4 and 5 servers.  ALL CENTOS servers have NTP setup to
sync time server.  Several days ago due to power outage all servers are reboot. 
Due to DNS server did NOT up quickly, CENTOS servers start up and can NOT find
time server.

For CENTOS 5.X servers, it did quickly resync to time server after 30 minutes.

For CENTOS 4.X servers, it have been 3 days still NOT sync to time server.  I
know I can run "service ntpd restart" to force server sync to time
server, but I like to know how long it take for CENTOS 4.X automatic resync to
time server.

Thanks.

> We have several CENTOS 4 and 5 servers.  ALL CENTOS servers have NTP setup
> to sync time server.  Several days ago due to power outage all servers are
> reboot.  Due to DNS server did NOT up quickly, CENTOS servers start up and
> can NOT find time server.
>
> For CENTOS 5.X servers, it did quickly resync to time server after 30
> minutes.
>
> For CENTOS 4.X servers, it have been 3 days still NOT sync to time server.
>  I know I can run "service ntpd restart" to force server sync to
time
> server, but I like to know how long it take for CENTOS 4.X automatic
> resync to time server.
man ntpd:
excerpt:
 Most operating systems and hardware of today incorporate a time-of-year
(TOY) chip  to  maintain  the  time  during periods when the power is
off. When the machine is booted, the chip is used to initialize the
operating system  time. After the machine has synchronized to a NTP
server, the operating system corrects the chip from time to time. In case
there is no TOY chip or for some reason  its  time is more than 1000s
from the server time, ntpd assumes something must be terribly wrong and
the only reliable action is for the operator to intervene and set the
clock by hand.
--- end excerpt ---

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