What time (server) is it?

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Loren Ryter Author

Level 3

549 points

What time (server) is it?

What time server does iOS use?

My Mac running OS X EC is more than 5 minutes ahead of my iPhone 6 and iPad (both currently running iOS 8.4).

I checked the following time servers with sntp in terminal:

sntp time.apple.com

sntp nist.netservicesgroup.com (US Standards, supposed to be synched with atomic clock)

sntp 0.us.pool.ntp.org

They are all within a few seconds of each other, and the same time as the Mac clock (set to automatic with time.apple.com)

But here's the odd thing. the site "time.is" is also supposed to be sychronized to the atomic clock. But that is showing the time that my iOS devices are showing, i.e., 5 minutes slower than the above servers. What's more, time.gov is showing the same time as time.is.

So what gives? Why the huge discrepancy? And again, what time server does iOS use??

Mac Pro, OS X El Capitan (10.11), iPhone 6, iPad 2

Posted on Mar 25, 2016 12:59 PM

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Answer 1

Loren Ryter Author

Level 3

549 points

Mar 25, 2016 11:42 PM in response to Loren Ryter

arg. ignore this. Turns out it's all based on misreading the output of sntp. I thought the output showed the correct server time. But it shows the system time and then the dreft in seconds:

sntp nist.netservicesgroup.com

2016 Mar 25 16:28:46.399196 -338.409283

So the iOS time was correct, time.is and time.gov was correct. The Mac was 5 minutes too fast.

Turns out this has to do with some problem with ntpd and pacemaker on OS X mavericks+ that is apparently still a problem. My personal solution was to create a launch daemon to run this terminal command (as root) every 24 hours:

/usr/sbin/ntpdate -u time.apple.com

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