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How to verify NTP is working ok on DC?

I have some Cisco gear complaining about NTP.  A couple of days ago I asked on here how to run a check to see if NTP was running.  You can see the command below. A couple more questions
today..  On the Windows 2008 server how can I see what the DC (10.10.10.139) is using as its NTP source?  Also - what are the d: and o: values in the output of the w32tm command below?  


C:\Users\medfly>w32tm /stripchart /computer:10.10.10.139 /samples:9
Tracking 10.10.10.139 [10.10.10.139:123].
Collecting 9 samples.
The current time is 10/8/2011 9:17:44 AM.
09:17:44 d:+00.0310000s o:+05.7559184s  [                           |
    *           ]
09:17:46 d:+00.0310000s o:+05.7578982s  [                           |
    *           ]
09:17:48 d:+00.0300000s o:+05.7517522s  [                           |
    *           ]
09:17:50 d:+00.1140000s o:+05.8054868s  [                           |
    *           ]
09:17:52 d:+00.0620000s o:+05.7797182s  [                           |
    *           ]
09:17:54 d:+00.0250000s o:+05.7505722s  [                           |
    *           ]
09:17:56 d:+00.0370000s o:+05.7535520s  [                           |
    *           ]
09:17:58 d:+00.0320000s o:+05.7560318s  [                           |
    *           ]
09:18:01 d:+00.0270000s o:+05.7565116s  [                           |
    *           ]
0
amigan_99
Asked:
amigan_99
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1 Solution
 
pritamduttCommented:
I am assuming your questions is find the source NTP server for your Windows 2008 DC.

If thats your question you can find out current NTP Server configuration in the following registry key.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\Parameters

or using the following command

w32tm /query /source

Open in new window


and regard d and o

D- Stands for Drift or Delay
O- Offset

Hope this helps...
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pritamduttCommented:
Also, this command should help you identify if NTP is working
w32tm /monitor /computers:time.windows.com,0.pool.ntp.org,1.pool.ntp.org

Open in new window


where computers could be any computer.

Hope this helps!
0
 
amigan_99Network EngineerAuthor Commented:

The o: Offset seems to keep incrementing. You can see when I posted just a while ago it was 5.75 and no it's over 6.  Earlier it was in the 4's.  Can you tell me what the offset means exactly?

C:\Users\medfly>w32tm /monitor /computers:10.10.10.139
10.10.10.139[10.10.10.139:123]:
    ICMP: 25ms delay
    NTP: +6.0800876s offset from local clock
        RefID: usno.pa-x.dec.com [204.123.2.72]
        Stratum: 2

Warning:
Reverse name resolution is best effort. It may not be
correct since RefID field in time packets differs across
NTP implementations and may not be using IP addresses.

One the server I see:


C:\Users\superuser>w32tm /query /source
usno.pa-x.dec.com,0x1
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pritamduttCommented:
The offset is the difference between the local time and an estimate based on the weighted average of the "best of the last 8" measurements made on the set of servers and peers chosen for disciplining the clock.

So you see it can vary depending on factors such as network latency/response time of server.
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amigan_99Network EngineerAuthor Commented:
Thanks much.  I think the problem is that CPU on the DC is spiking
causing service availability issue intermittently.  

BTW - the offset is in milliseconds?
0
 
pritamduttCommented:
Thanks ..

The offset is in seconds... see a s at the end... o:+05.7559184s
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