Prerequisites for the scenario are as follows:
Enable the feature in the settings of a Download updates to the repository of the Administration Server task.
Enable the feature for a distribution point that receives updates by means of a Download updates to the repositories of distribution points task.
Then enable the feature for a distribution point that receives updates from Administration Server.
The feature is enabled in the Network Agent policy settings and—if the distribution points are assigned manually and if you want to override policy settings—in the Distribution points section of the Administration Server properties.
To check that the Downloading diff files feature is successfully enabled, you can measure the internal traffic before and after you perform the scenario.