Leap seconds are supported by ntpd. Leap seconds are announced in advance at this fixed URL, which also contains the list of past leap seconds: https://www.ietf

Leap seconds are supported by ntpd. Leap seconds are announced in advance at this fixed URL, which also contains the list of past leap seconds: https://www.ietf.org/timezones/data/leap-seconds.list https://www.ietf.org/timezones/data/leap-seconds.list ...which can be added to ntpd's configuration if you want your system's leap second to occur exactly on time. Even if you don't, the leap second will eventually take effect via an update from your configured remote ntp servers, or your GPS source, or wherever you get your time from.