# Known leap second problems

**URL:** <https://community.ntppool.org/t/known-leap-second-problems/53>\
**Category:** Uncategorized\
**Created:** [December 30, 2016, 6:48am UTC](https://community.ntppool.org/t/known-leap-second-problems/53 "2016-12-30T06:48:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ask](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/ask/32/907_2.png) [@ask](https://community.ntppool.org/u/ask)\
**Post date:** [December 30, 2016, 6:48am UTC](https://community.ntppool.org/t/known-leap-second-problems/53/1 "2016-12-30T06:48:38Z")

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The [leap second](https://en.wikipedia.org/wiki/Leap_second) is less than two days away. The NTP Pool system will monitor (as always) the servers in the pool and remove servers that divert in time. In past years a small number of servers would be off by a second for a few hours (or sometimes a few days) after the leap second insertion.

Red Hat published a list of [known leap second issues in (Red Hat) Linux](https://access.redhat.com/articles/15145#known).

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**Author:** ![josephb](https://sea2.discourse-cdn.com/flex016/user_avatar/community.ntppool.org/josephb/32/7_2.png) [@josephb](https://community.ntppool.org/u/josephb)\
**Post date:** [December 30, 2016, 12:39pm UTC](https://community.ntppool.org/t/known-leap-second-problems/53/2 "2016-12-30T12:39:44Z")

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Various Cisco IOS-XE and NXOS issues exist which impact ASR 1K and Nexus router/switch platforms.

Recommendation is to upgrade software, or disable NTP at least 24 hours prior to the leap second event.

A good place to start:

[http://www.nts.eu/en/networksecurity-en/linux-kernel-crashes-due-leap-second-injection/](http://www.nts.eu/en/networksecurity-en/linux-kernel-crashes-due-leap-second-injection/)