Microsoft is adding support for leap seconds in Windows

Microsoft yesterday revealed that it is improving the time accuracy on Windows with several new features such as the support for Precision Time Protocol, support of leap seconds and more in Windows. The upcoming Windows Server 2019 will include the following improvements.

• Compliant Leap Second Support
• Accuracy Improvements (Precision Time Protocol, Software Time-stamping, Clock Source Stability)
• Traceability (including system logging, performance counters, and our work with partners)

Compliant Leap Second Support:

In general, computers maintain seconds ranging from 0 to 59 for a total of 60 seconds. When a leap second occurs, an extra second will be added to the last minute of the UTC day and the computers will keep seconds 0 through 60 for a total of 61 seconds.

Why do we add an extra second?

As the earth’s rotation slows, UTC (an atomic timescale) diverges from mean solar time or astronomical time.  Once UTC has diverged by at most .9 seconds, a Leap Second is inserted to keep UTC in-sync with mean solar time.

Precision Time Protocol:

Precision Time Protocol allows network devices to add the latency introduced by each network device into the timing measurements thereby providing a far more accurate time sample to either Windows Server 2019 or Windows 10 machine, host or virtual machine. Microsoft mentioned that the current Network Time Protocol (NTP) used in Windows will continue to be the default protocol.

Traceability:

With the upcoming Windows Server 2019 release, Microsoft will add additional logging capabilities that can be used to audit the actions taken by the Windows Time service.

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