May 20 2011

Group Policy Loopback Processing

Until recently I hadn’t ever played with loopback processing in group policies. I was having problems with group policies not being applied and found that this setting was enabled. When I looked into it this is what I found.

There are two settings for the Loopback Processing settings (detailed below).

  • Merge Mode
    In this mode, when the user logs on, the user’s list of GPOs is typically gathered by using the GetGPOList function. The GetGPOList function is then called again by using the computer’s location in Active Directory. The list of GPOs for the computer is then added to the end of the GPOs for the user. This causes the computer’s GPOs to have higher precedence than the user’s GPOs. In this example, the list of GPOs for the computer is added to the user’s list.
  • Replace Mode
    In this mode, the user’s list of GPOs is not gathered. Only the list of GPOs based on the computer object is used.

More information can be found at Microsoft support (http://support.microsoft.com/kb/231287).