Question: I would like to know what the default settings for OS X are in terms of keeping the clock adjusted when I enable automatic time sync in the Date & Time preference.

I do know that the venerable `ntpd` daemon on Mavericks (10.9) and Yosemite (10.10) is no longer responsible for adjusting the time and instead a new program `pacemaker` has been introduced — so how can I know things are working or need adjustment to keep time?

Answer: 
If you go to <http://time.gov> you can see the official time (up to the second) and use that to verify if your system time is correct or not. Note that this is the official NIST time, and does its own synchronization in the browser, independently of the system time (as an example, you can see [here](https://www.dropbox.com/s/9gfgg6lp7rmsib3/Leap%20Second.mov?dl=0) that time.gov handles leap seconds, whereas OS X apparently does not).
To get a reliable answer on how well your clock is set, run ntpdate in debug mode:

```
ntpdate -d pool.ntp.org

```

This will gyrate for a while and end in a line such as

```
 1 Apr 17:38:16 ntpdate[4711]: adjust time server 123.45.67.89 offset 0.000810 sec

```

In this case, this meant to say my local clock was off some 810 µs (which would be spectacular, if actually true, but the value well below 100 ms does indicate a working synchronization).