Contributed By: Tony Hobson [updated 07/05/04]
SUS is a very important tool for us and for our RAS Users, I needed to know more precisely the detection cycle if no connection to the server specified could be made at the DetectionStartTime specified. Important for Road Trippers using DUN at Hotels, etc. After testing it seems to work like this:

1. First detection attempt made at start of Automatic Updates service + time specified in HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU\RescheduleWaitTime.
    
2. If no connection can be established to the Server specified, the value HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\LastWaitTimeout is set to what appears to be a random time between 5 and 10 minutes from the detection attempt.
   
   Note: LastWaitTimeout value looks to be set in GMT.
    
3. At the time specified in LastWaitTimeout the detection is tried. If no connection can be made the LastWaitTimeout is reset to 10 minutes from the detection attempt. This is the pattern followed from then on.

Hope this might assist someone.

Contributed By: Cliff Hobbs [MVP SMS]
By default the client performs and Automatic Detection Cycle every 17 - 22 hours.  If you want to force the Client to perform a detection cycle then follow the instructions in Microsoft Knowledge Base Article 326693 'How to Force Automatic Updates 2.2 to Perform a Detection Cycle'.