1. So, what does “GPO refresh interval” mean?
Every 90 minutes + a random interval (more on that later) your Windows Workstations will ask your Domain Controller for the most current Group Policy Objects applied to that computer/user.
This means if an administrator has made some changes to a GPO. Within 90 minutes + 30 minutes, the new GPO changes will be applied to the computers/users. Nowadays many don’t restart their computer very often, so this refresh interval is a very good thing.
TLDR; refresh interval = the computer/user asks for updates on the GPOs applied to it.
2. Time period
By default, the time period between refreshes is 90 minutes + a random offset. The random offset is between 0 and 30 minutes.
This is to avoid a lot of requests to the domain controller at the same time.
Imagine a company where everyone begins their work at 8 in the morning. Without the random offset, a lot of GPO refreshes will hit the DC at 09:30 AM. To avoid all this simulations traffic, the offset was created.
3. How to change the refresh interval + offset
You can change the interval and offset with Regedit, but it is not recommended. Instead, I will show you how to do it with a GPO.
There are 2 different GPO settings for adjusting the time periods. One for adjusting the computer configuration refreshes and one for the user configuration
3.1 Computer configuration
Computer Configuration > Policies > Administrative Templates > System > Group Policy > Set Group Policy refresh interval for computers.
If you want to disable it, there is a setting called “Turn off background refresh of Group Policy”
3.2 User configuration
User Configuration > Policies > Administrative Templates > System > Group Policy > Set Group Policy refresh interval for users.
4. Preferences are not included in the background refreshs
Just a friendly reminder, that preferences are only applied when you startup and logon into the machine. Background refreshes are only for Policies.
Source: Active Directory released by O’Reilly page 314.