[CentOS] leap second

Mon Jul 2 18:55:36 UTC 2012
Gordon Messmer <yinyang at eburg.com>

On 07/02/2012 10:37 AM, Peter Eckel wrote:
> they do. But the leap second is quite a different thing: Actually the
> time doesn't really diverge from the server's, but the stratum 1
> server deliveres a totally unexpected 01:59:60, and the stratum 2
> server follows.

That's not quite correct.  The NTP protocol (as you mentioned later) 
actually indicates that the current day should include a leap second, 
the NTP server notifies the kernel that the day should include a leap 
second, and the kernel inserts the leap second at the end of the day by 
extending the duration of one of the system clock's seconds.

The "60" second doesn't exist in NTP or in the POSIX system clock, both 
of which are counters from their respective epochs.  The "60" second is 
present only in time representations that are converted from the system 
clock or NTP clock.