Five different ways to handle leap seconds with NTP

I’m starting to write a detailed description about how we’ll tackle the leap second. In the meanwhile you can well read this very beautiful and informative piece by Miroslav Lichvar. His observations about the behaviour of ntpd match mine and will give you an idea of how our solution works.

Red Hat Developer Blog

A leap second is an adjustment that is once in a while applied to the Coordinated Universal Time (UTC) to keep it close to the mean solar time. The concept is similar to that of leap day, but instead of adding a 29th day to February to keep the calendar synchronized with Earth’s orbit around the Sun, an extra second 23:59:60 is added to the last day of June or December to keep the time of the day synchronized with the Earth’s rotation relative to the Sun. The mean solar day is about 2 milliseconds longer than 24 hours and in long term it’s getting longer as the Moon is constantly slowing down the Earth’s rotation.

UTC is based on the International Atomic Time (TAI) and it is currently 35 seconds behind TAI. The first leap second was inserted in 1972 and 25 seconds were inserted so far. The next…

View original post 2,661 more words

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