How long does it take to update all the clocks in a Windows domain?

Question

I know the answer to this might be a bit nebulous, so I'll happily accept an answer that tells me the basic rules for this.

Supposing the clock in the PDC Emulator has got all out of whack and this has sent all the workstation clocks similarly out of sync. Once the DC has been reset (and other important servers), how long would you expect the rest of the computers to take to update? Assuming everything else is in working order, of course.

score 3 · Accepted Answer · answered Nov 19 '13 at 16:36

There are a few parameters that control this, but I believe the default is the MinPollInterval and MaxPollInterval. You can check it on a client (see below) to finding the polling interval.

There's also a "specialpollinterval" (see here:http://blogs.msdn.com/b/w32time/archive/2009/02/02/group-policy-settings-explained.aspx) if it is enabled. I believe the default is 1 hour (specialpollinterval).

You can run w32tm /monitor on a client to see what the current offset is to the DC.

You can use w32tm /query /status to get the actual Poll interval, such as:

C:\WINDOWS\system32>w32tm /query /status
Leap Indicator: 0(no warning)
Stratum: 2 (secondary reference - syncd by (S)NTP)
Precision: -6 (15.625ms per tick)
Root Delay: 0.0634819s
Root Dispersion: 1.7993795s
ReferenceId: 0xA5C17EE5 (source IP:  165.193.126.229)
Last Successful Sync Time: 11/19/2013 9:47:27 AM
Source: time.nist.gov,0x9
Poll Interval: 10 (1024s)

You can check the full configuration using w32tm /query /configuration.

You can also force a sync using w32tm /resync or stopping/starting w32time service on the clients. You can even specify the client that will resync in the /resync parameter (check the /? help).

I found that `w32tm /monitor` indicated a 0s offset from the PDC, although according to `net time` my machine was about 4 minutes ahead of the PDC. Do you know what the offset actually means? — Holistic Developer, Nov 17 '14 at 20:55

score 1 · Answer 2 · edited Nov 19 '13 at 18:25

1

Depends. An hour or two - BUT: machines may reject the new time until restarted. They wont update if the difference is too big, assuming the PDC emulator is wonky. This requires a script to run to force a sync - or a restart. I would push a script onto all machines to run a forced sync.... a proper larger org should have tools for that (SCOM).

edited Nov 19 '13 at 18:25

Zoredache

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answered Nov 19 '13 at 16:31

TomTom

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How long does it take to update all the clocks in a Windows domain?

2 Answers2