Erroneous Leap Second Introduced at 2014-06-30 23:59:59 UTC

[Tim Heckman <t () heckman io>]

Hey Everyone,

I just was alerted to one of the systems I managed having a time skew
greater than 100ms from NTP sources. Upon further investigation it
seemed that the time was off by almost exactly 1 second.

Looking back over our NTP monitoring, it would appear that this system
had a large time adjust at approximately 00:00 UTC:

- http://puu.sh/9Rs6O/a514ad7c97.png (times are in Pacific in these
graphs, sorry about that)

A few of our systems did alert early this morning, indicating they
were going to be receiving a leap second today. However, I was unable
to determine the exact cause for NTP believing a leap second should be
added. And after some time a few of the systems were no longer
indicating that a leap second would be introduced.

This specific system is hosted in AWS US-WEST-2C and uses the
0.amazon.pool.ntp.org pool.

Has anyone else seen any erroneous leap seconds being added to their system?

Cheers!
-Tim Heckman