3. Cautions

Leap seconds are inserted at the same instant all over the world: UTC midnight. In Japan that is mid-morning, in the Pacific mid-day, in the Americas late afternoon, and in Europe at night.

We believe and expect that FreeBSD, if provided correct and stable NTP service, will work as designed during this leap second, as it did during the previous ones.

However, we caution that practically no applications have ever asked the kernel about leap seconds. Our experience is that, as designed, leap seconds are essentially a replay of the second before the leap second, and this is a surprise to most application programmers.

Other operating systems and other computers may or may not handle the leap-second the same way as FreeBSD, and systems without correct and stable NTP service will not know anything about leap seconds at all.

It is not unheard of for computers to crash because of leap seconds, and experience has shown that a large fraction of all public NTP servers might handle and announce the leap second incorrectly.

Please try to make sure nothing horrible happens because of the leap second.

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