David J Taylor wrote:
Chuck Swiger wrote:
David J Taylor wrote:
[]
Doesn't iburst violate the "more than 5 per minute" rule?
Yes. But with the default NTP settings, it shouldn't violate the old
20 requests/hour guideline. iburst should be reserved for hosts
providing NTP services to other machines, and not used by end-client
workstations.
Time to start a different thread, perhaps.
My understanding of iburst is that it is for /any/ NTP client, whether
providing downstream services or not. Indeed, it is particular
appropriate for end-client workstations which may be up and down more
than servers, and therefore have more need of the quick synchronisation
which iburst can provide.
If you are using your clients against your NTP servers on a LAN, iburst is fine.
However, it's not needed by clients by definition, because nobody else is asking
them for time, so whether ntpd is synced is has vey little bearing on the
accuracy of local time.
(Unless your ToD/BIOS hardware clock is seriously busted-- if you've ever been
able to sync to NTP, ntp.drift will be calibrated to compensate. [1])
You probably should not use iburst against someone else's server without asking
them for permission or their access policy permits rapid updates.
Note that Apple recently changed their defaults to "minpoll 12 maxpoll 17" for
time.apple.com. That's 1+ hour (4096 seconds) and 36-hours, respectively.
Clients should poll remote NTP servers at once-an-hour internals or less
frequently by default; polling quickly to start up is reasonable and useful for
servers, but it just doesn't matter for pure clients.
--
-Chuck
[1]: If your client's hardware clock is so unreliable that you have to ask
someone else's server what time it is more often than once a minute, run a local
NTP server yourself on another machine with a working clock, or get a GPS unit,
rather than abusing non-local NTP servers, if you please.
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