ntp sync frequency

[huffman at graze.net]

To quote the NTP documentation - which answers both of your questions:

"Ordinarily, and in most operating environments, the state machine will start
with 64s intervals and eventually increase in steps to 1024s. A small amount of
random variation is introduced in order to avoid bunching at the servers. In
addition, should a server become unreachable for some time, the poll interval is
increased in steps to 1024s in order to reduce network overhead.

In some cases it may not be practical for ntpd to run continuously. A common
workaround has been to run the ntpdate program from a cron job at designated
times. However, this program does not have the crafted signal processing, error
checking and mitigation algorithms of ntpd."

To echo what the documentation states, great care is taken in the NTP daemon
(along with proper configuration) to ensure accuracy and redundancy of your time
source.  In addition, due to the granularity that the daemon uses when "slewing"
the clock, it is preferable for any applications that might be susceptible to
large time jumps.

I would not use the ntpdate out of cron unless *absolutely* necessary....

Brian

nina at gibbons.com,  For users of Fedora Core releases
<fedora-list at redhat.com> wrote: 
> by default, how often ntpd does the synchronization? can we change the 
> time interval? What are the pros and cons running ntpd? Alternative way 
> of ntpd is running cron. I think by running cron, we have more control 
> over time synchronization.
> 
> Nina
> 
> 
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