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Leap Second Information for AIX

Question & Answer


Is the AIX Operating System affected by the leap second adjustment?


On December 31, 2016, during the last second of the day, a new leap second will be added to global time.
AIX does not have -- and never has had -- any direct awareness of the leap second. There have been several leap seconds over the years through the history of AIX, with no known AIX issues reported. However, the NTP (Network Time Protocol) daemon is available on AIX for those who need precise time synchronization with other systems.

AIX systems may fall into one of three scenarios:
1) Sub-second synchronization not an issue; no NTP in use. The system will run as normal, unaware that its own time is one second offset from where it had been previously.
2) System time synchronization needed: use NTP daemon. Your AIX system can run the NTP time service as a client, synchronizing to another system or an external time server (e.g. The NTP client will slowly adjust the system clock to stay in sync with the time server, thus accommodating the leap second.
3) The AIX system is itself acting as a primary NTP master server, without in turn being a client of another time server. This is rare and not recommended if you need sub-second time synchronization, but if you do need to configure your system in this way, you can do so following the instructions at – specifically (as of this writing)

Most systems will be in scenario #1 or #2 and will not need to take any action.

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Document Information

Modified date:
15 September 2021