This article applies to Domain Time II.

Last Updated: 23 May 2002

Question

How do I control when Domain Time II overrides the maximum disparity setting?

Answer

Disparity refers to how far off from the correct time your machine is. Domain Time II Servers and Clients let you specify a maximum value for this disparity; potential corrections greater than your maximum are not applied.

The purpose of having a maximum disparity is to keep your machine from accepting time from a server that has "gone mad." Mad servers, also called "false tickers," are servers that don't know they are serving incorrect time. Servers normally express, along with the time, an opinion of whether or not their time is correct. A mad server will say its time has been verified when in fact it hasn't.

There are times, however, when your machine cannot tell the difference between a mad server and a genuine correction of several minutes or even several years. For example, right after rebooting, your machine is dependent on the built-in real-time clock, which runs on a battery. A problem with the real-time clock could yield a date of January 1, 1980 (a common value for older BIOSes). When this happens, you don't want Domain Time to reject the correction. In these instances, you will want to override the max disparity settings to allow Domain Time to make any size correction necessary.

Information on versions 2.5.b.20020521 through 4.1


In general, Domain Time overrides the maximum disparity when it has reason to doubt its own time. In automatic mode (the default), Domain Time will accept any amount of correction right after startup, when a user or process changes the time manually, or when the administrator asks the machine to sync (either from the control panel applet, dtcheck, or Domain Time II Manager).

You may add a registry value called Override Max Disparity to control this behavior:

• Server
• Full Client
  
• Thin Client
  

Information on versions 5.x and later


Domain Time now allows much finer control of when to override the max disparity settings than earlier versions. The Clock Control property page of the Domain Time Server and Client control panel applets lets you configure how you want corrections to be made (Slewed vs Stepped), and the Stepping Options dialog allows you to select exactly which events you want to allow to override the disparity settings you made on the Correction Limits property page.