How do I interpret w32tm output, especially d:?

Question

I am trying to understand what all the different values mean in the following output. I understand the command below is comparing my local time ("current time is") with time.nist.gov

8:38:08 is my local workstation time.

What does the value in d: mean? What does the value in o: mean?

C:\>w32tm /stripchart /computer:time.nist.gov
Tracking time.nist.gov [131.107.13.100:123].
The current time is 3/5/2015 8:38:08 AM.
08:38:08 d:+00.0311860s o:+00.2011040s  [                           |*                          ]
08:38:10 d:+00.0311843s o:+00.1896103s  [                           |*                          ]
08:38:12 d:+00.0311849s o:+00.1905021s  [                           |*                          ]

I think I understand o: to mean that if I take my current time and add the o: value, then my local time will be in sync with remote time. I tried by adjusting my time ahead a few seconds. Since the o: value changed to -00.3849046s, I assume that means my local time is ahead and I need to slow it down to be in sync:

C:\>w32tm /stripchart /computer:time.nist.gov
Tracking time.nist.gov [24.56.178.140:123].
The current time is 3/5/2015 8:43:06 AM.
08:43:06 d:+00.0467946s o:-00.3849046s  [                          *|                           ]
08:43:08 d:+00.0311896s o:-00.3815899s  [                          *|                           ]
08:43:10 d:+00.0439942s o:-00.3595516s  [                          *|                           ]

This also leads me to believe the | symbol is local time and the * is the remote time. * to the left means your time is ahead. * to the right of it means your time is behind.

That still leaves d:... is that ping latency? Do I need to add those seconds with o: to get the final time of the remote time server?

Solution

How do I interpret w32tm output?

08:38:08 d:+00.0311860s o:+00.2011040s

• 08:38:08 is local time

• d:+00.0311860s is the internal delay (time difference between the udp package received and udp package sent on the server side

• o:+00.2011040s is actual offset between the local time and the server time

---

That still leaves d:... is that ping latency?

Do I need to add those seconds with o: to get the final time of the remote time server?

The o: is the actual offset, so you don't need to add the d: to get the final time.

---

The console application w32tm.exe allows monitoring of the offset of the local time to the time of an internet time server.

The easiest way to do this is from a console window with the following set of parameters:

w32tm /stripchart /computer:time.windows.com /period:120

As a result, the system time and its offset to the time server are dumped to the console every 120 seconds:

Tracking time.windows.com [65.55.21.14.123]

08:38:57 d:+00.0417301s o:+00.1024506s [ * ]

Each line consists of the local time (08:38:57), an internal delay (time difference between the udp package received and udp package sent on the server side, i.e., d:+00.0419394s), the actual offset between the local time and the server time (o:+00.1024506s) and a very basic stripchart of the offset.

Source Part II: Adjustment of System Time

Comments

[Sun]

I see. So, O adds d: to its calculation to arrive at the final value. I understand I can ignore d: to see how much offset there is between local time and server time.

[Sun]

Just to be explicit, when you see O value with a +, you must add that amount of time to match the server time. If it is -, you must subtract that much time to match the server time.