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Timings Timings
Domain Time II Server
Version 5.2

Settings on this page control how often time checks are performed when querying servers for the time (if using normal NTP or DT2 protocols) or how often samples are coalesced for statistics/alerting if using PTP.

Note: If Domain Time Server on this machine is set as a Slave server, this page will not appear since Slaves inherit their timing settings from the Master server. See Domain Roles for more information on Master, Slave, and Independent Server roles.

Timings for broadcast NTP or DT2 are set on the Serve the Time property page. The settings on this page do not apply if you are using the Broadcast/Multicast method of obtaining network time.

If you see the Policy Applied Group Policy applied indicator in the lower-left corner of the applet, there are settings on this page that are being overridden by an Active Directory Group Policy. Settings controlled by policy may be greyed-out or you may be otherwise prevented from making a change here. See the Active Directory page for more information on using Group Policies.


There are two scheduling options for determining how often Domain Time checks the time/reports statistics:

 Check Interval when able to get and correct the time 

Variable - check as often as needed to maintain approximately milliseconds sync with server
 Fixed - check once every  

    Variable - check as often as needed to maintain approximately milliseconds sync with server

    When this option is selected, Domain Time will automatically adjust how often it synchronizes with time sources to attempt to keep the clock within the threshold limit you set.

      The wait period between time checks is called the window size. You can see the window size Domain Time is currently using by examining the Text Log. Domain Time will adjust the window size based on how accurate previous time checks have been. If previous time corrections have been small the window size will be increased, and vice versa. The range of adjustment for the window size is between 15 seconds to 2 hours. On most machines, it will average between 10 - 30 minutes.

      The Variable scheduling method is intended for use on machines with relatively constant clock drift and moderate accuracy requirements (where the acceptable tolerance for clock drift is more than ~25ms). This method is a good for general-purpose use, primarily on Clients, since it strikes a good balance between maintaining the target accuracy while minimizing network traffic.

      Variable is not a good selection if the machine is under heavy and/or variable load that causes the clock to drift by significant amounts on an irregular basis. Since Domain Time may select a large window size if the clock on the machine has been well-behaved, anything that causes sudden clock drift during the Window period between checks can cause the clock to drift outside the specified threshold before the next correction. If this describes your machine, you should use the Fixed schedule instead.

     Fixed - check once every  

    If this option is selected, Domain Time will synchronize regularly on the schedule you specify.

      This method is a good choice when you want to discipline the clock to stay within very tight synchronization tolerances. It's also the best choice for machines with highly variable load, poor timekeeping hardware, or any other issue that causes significant clock drift.

      You should check the time often enough to keep your clock within your desired accuracy.

      Since having highly-accurate time at all times is usually more critical on Servers, you will likely want to check often using a fixed schedule on Servers.

      CAUTION: Take care with this setting. Many time servers have Denial-of-Service (DOS) protection to prevent abuse. Issuing too many time requests in a row to one server over a short period of time can cause your machine to be locked out or even be permanently blacklisted.

      This problem can be exacerbated if you have opted to collect multiple samples per time source. See About Time Samples.

      See the "Finding the Sweet Spot" sidebar on the right for more info on picking the correct sync rate.


 Check Interval when getting the time fails 

If Domain Time cannot
obtain the time, it should   
try again every:

You may set a different rate for Domain Time to use if it cannot contact any time source.

    If Domain Time cannot obtain the time, it should try again every:  
    sets how often Domain Time will retry its time sources if it is unable to successfully obtain the time. You will probably want to check more often than during normal operation (unless you're already using a frequent synchronization schedule) to reacquire the correct time quickly when your time source(s) become available.

    The same caution about synchronizing too often against your time sources (discussed above) applies.


Next Proceed to the Correction Limits page
Back Back to the IEEE-1588 (PTP) page

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