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W32time service again...

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by john r. richards, jr.

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I recently installed/configured the w32time service on my NT4 network. My goal is to synchronize time on my servers only - SMS handles time updates for all of our clients.
I would like to configure my NT4 PDC as a Master Time Server, and then manually point my remaining NT4/Win2000 servers to it - no broadcasts.

My NT4 PDC has W32time configured as follows:

Type=NTP
NTPServer= a valid IP for a UNIX NTP server on our corporate network
Log=yes
LocalNTP=no

This functionality works fine.

Next, I configured one of my Win2000 servers with the NET TIME \\PDC /SETSNTP command. After restarting the time service, the time jumped several minutes to correspond to the time on the PDC.

I continued to run this command on my remaining Win2000 servers. Then I installed/configured the W32time service on my remaining NT4 servers. The NT4 member servers were configured as follows:

Type=PRIMARY
PrimarySource=\\PDC_NAME
timesource=no

All of my servers, both Win2000 and NT4 synced up fine. I just have one issue:

When I run the NET TIME command on any of my servers, Win2000 or NT4, it returns the time and Netbios name from the first Win2000 member server I configured. As a matter of fact, clients will return the same server name and time.

I was under the impression that my servers/clients should be receiving time from the PDC, and should report this with the NET TIME command.

Why is this happening?

Thanks,

JR

11 replies

by ann777

Check these out:

http://www.jsiinc.com/sube/tip2400/rh2466.htm

http://www.jsiinc.com/subg/tip3100/rh3138.htm

http://www.jsiinc.com/subi/tip4200/rh4240.htm

http://www.jsiinc.com/sube/tip2200/rh2293.htm

http://www.jsiinc.com/subd/tip1700/rh1782.htm

http://www.jsiinc.com/subi/tip4100/rh4167.htm

http://www.jsiinc.com/subf/tip2800/rh2859.htm

http://www.jsiinc.com/sube/tip2300/rh2337.htm

http://www.jsiinc.com/subg/tip3400/rh3429.htm

http://www.jsiinc.com/subf/tip2600/rh2669.htm

http://www.jsiinc.com/sube/tip2200/rh2273.htm

http://www.jsiinc.com/subi/tip4000/rh4075.htm

by shanghai sam

JSI was one of the first places I looked. Lot's of good articles - just nothing specific to my question.
Thanks for the input though.

JR

by maxwell edison

The Windows Time (W32Time) service for Windows 2000 does a better job than TimeServ or NET TIME, but can be difficult to configure and monitor, time-intensive to administer, and has significant limitations in functionality. Windows Time is (usually)accurate enough to keep Kerberos working, but is insufficient for any other synchronization purpose.

Two-second accuracy target
Windows Time only attempts to keep the time on each machine synchronized within two seconds of its source. In practice, this yields a 2-4 second consistent variance among machines when everything is configured correctly and working perfectly. The two-second target is not configurable.

Auto-discovery doesn't work with SNTP
By default, SNTP is only used by the PDC (after you've enabled it). Other participating machines use the LAN Manager protocol (the same as NET TIME) to coordinate with the PDC. The maximum accuracy of the LAN Manager protocol is one tenth of a second, but it does not account for LAN/WAN latencies, and can be wildly off. You can set individual machines to use SNTP instead of LAN Manager, but then you lose automatic discovery of servers. When operating in SNTP mode, machines use the servers you specify from the command line on eachmachine.

Limited-value SNTP time server
By changing a registry setting, you can set Windows Time to function as an SNTP time source for interoperation with other programs. However, the time served is only accuracte to the level of accuracy on that machine, which is targetted to two seconds, but often fails to achieve this.

(continued...)

by maxwell edison

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No default time source
The FSMO PDC can obtain its time via NTP/SNTP (RFC 1769) from a trusted source, such as the US Naval Observatory. But by default, it doesn't use a trusted source at all; it just assumes its own time is correct. You canset the source by using the NET TIME /SNTP:source command in a command window on the PDC.

No propagation of settings
The trusted source information is not propagated from the FSMO PDC to other Domain Controllers. If a BDC is promoted to PDC, it will begin using whatever trusted source was set on the BDC (by default, nothing).

No support for non-Windows 2000 machines in the time hierarchy
Each machine, at boot time, nominates an "inbound time partner." For BDCs, this is the PDC. For member servers and workstations, this is the BDC that authenticated the machine onto the domain. This behavior is not configurable, and means that machines that aren't part of a Windows 2000 domain (all Win95/Win98 machines, NT machines in a workgroup, and NT machines in a domain without a PDC running Active Directory) cannot participate in domain-wide time synchronization. They must use the NET TIME command, usually in a logon batch file.

(continued...)

by maxwell edison

.
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No time-changed notifications
No attempt is made to cascade time changes throughout the domain. If the time changes on the PDC, each BDC will discover the change up to eight hours later. Member servers and workstations follow their own schedule when checking with their designated BDC, so the aggregate lapse between when the time changes on the PDC and when the new time is recognized at a workstation averages eight hours, and can be as large as 16 hours. This means that, at any given time, a pure Windows 2000 domain with each machine running Windows Time could have a system-wide variance of two to four seconds, but still be considered synchronized! In practice, with eight to sixteen hours between checks, the domain will probably have a variance in excess of several minutes. You can use our FREE LMCheck utility to test your system's performance without installing any additional software.

No statistics or domain-wide sync triggers are provided
You cannot query the Windows Time service to determine if it is working properly, when the last time set occurred, who the inbound time partner was, or when the next time set is scheduled (although some of this information is usually available from the command-line on each machine using the w32tm program). You cannot determine the amount of adjustment applied, or the variance among machines. You cannot trigger a sync of the entire domain. The only way to trigger a sync for a specific machine is to use the w32tm command-line utility or manually stop and restart the Windows Time service. To know whether or not it worked, you must watch the clock display and see if it changes or examine the event log for errors.

Maxwell

by shanghai sam

I can't find a direct answer to my original question in your response. "Why do my member servers respond to a "Net time" command with the name of another member server and the time on that server?" I would think they would respond with the name ofthe PDC I pointed them to with the SETSNTP switch.

But, you have provided enough helpful information that I haven't received elsewhere. So I am awarding you the techpoints for this answer.

I appreciate your help.

John Richards
Lucent Tech.

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