[ntp:questions] NTP - best practice if there is a local stratum 2 server
nomail at example.com
Sun Jun 28 18:01:23 UTC 2009
Dave <foo at coo.com> wrote:
> I assume, for absolute accuracy (which is not important here, but I'm
> intersted), this is going to be better than any attempt to set the time
> from the ntp pool. Is that correct?
You never know that.
What you get from the pool may be a stratum-1 server locked to GPS time
on a fast unloaded connection, or it may be a slow box on a saturated
ADSL line and synchronized to time.windows.com.
Your local server will be better to depend on. You at least know what
you get, and/or you can ask the department it belongs to what quality
you can expect. You can never do that with the pool.
> But setting the time from the local server is also going to be cause a
> problem if that server fails for some reason.
> Is there any way to make use of a local server if it's working, and then
> use the pool if its not?
Of course. When you configure the local server as a "prefer" server, it
will usually work out that way.
> To be honest, this is all a bit academic, as there is no real practical
> need to have an accuracy of better than a minute or two on these
> machines. In fact, an hour wrong would not make much difference but it
> might irritate a few people.
> But it is important the two machine agree with each other, as otherwise
> files appear to be created in the future by a few ms, which screws up
> the 'make' program some times.
Then you should, as you do, synchronize one to the other or both of them
to the same (local) third server.
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