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Time synchronization is one of the most important dependencies of Windows. A time protocol is responsible for determining the best available time information and converging the clocks to ensure that a consistent time is maintained across systems. By default, Windows supports a tolerance of plus or minus five minutes for clocks. If the time variance exceeds this setting, clients will be unable to authenticate and in the case of domain controllers, replication will not occur. To avoid this, Windows implements a time synchronization system based on Network Time Protocol (NTP).

NTP is a fault-tolerant, highly scalable time protocol and it is used for synchronizing computer clocks by using a designated reference clock. A reference clock is some device or machinery that spits out the current time. The special thing about these things is accuracy. Reference clocks must be accurately following some time standard. NTP will compute some additional statistical values based on the current time reported by the reference clock, which will describe the quality of time it sees. Among these values are: offset (or phase), jitter (or dispersion), frequency error, and stability. Thus each NTP server will maintain an estimate of the quality of its reference clocks and of itself.

This test reports the time difference between the reference clock and that of the target environment, and thus helps assess the quality of time seen by the Azure virtual desktop. With the help of this test, you can also easily determine whether the reference time changed recently.

Measurement	Description	Measurement Unit	Interpretation
NTP_offset	Indicates the time difference between the local clock and the designated reference clock.	Secs	For a tiny offset, NTP will adjust the local clock; for small and larger offsets, NTP will reject the reference time for a while. In the latter case, the operating system's clock will continue with the last corrections effective while the new reference time is being rejected. After some time, small offsets (significantly less than a second) will be slewed (adjusted slowly), while larger offsets will cause the clock to be stepped (set anew). Huge offsets are rejected, and NTP will terminate itself, believing something very strange must have happened.