[time-nuts] How are iPhones' clocks set under LTE?

Paul tic-toc at bodosom.net
Tue Aug 5 09:18:25 EDT 2014


On Tue, Aug 5, 2014 at 3:24 AM, David J Taylor
<david-taylor at blueyonder.co.uk> wrote:
> Seems to work correctly here - my local stratum 1 server is displayed if
> it's reachable (i.e. I'm on my local network).

In the US it tries [0-3].us.pool and my local address.  It chooses the
"best" three of those and then it chooses one.  The list also shows
(in pool.ntp.org) [0-3],  europe,  north-america. asia. oceania,
south-america and time.apple.com in that order.  Is it the same in the
UK?

In March 2013 (it seems longer ago):
>ET asynchronously sends an NTP request to each of 4 or 5 hosts.  It then requests additional >samples from each host until it gets enough good samples from at least one host.  It then picks the >host whose times were most consistent (the lowest "sigma" value in the stats display).  Since all >this is happening asynchronously we may stop before getting a full complement of responses from >each host.  And it may not be the host with the lowest RTT.
>
>ET was our first app that uses NTP.  We have since switched to a different algorithm for picking >which server to use in our other apps.  But so far the new algorithm hasn't been incorporated into >ET.
>
>William Arnett
>Emerald Sequoia LLC"


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