VMware Blast policy settings are stored in the registry key HKLM\Software\Policies\VMware, Inc.\VMware Blast\Config on the remote desktops or RDS hosts that use the VMware Blast display protocol. These settings can be configured by using the VMware Blast ADMX template file (vdm_blast.admx) and applying it through Microsoft Group Policy Object (GPO). Some of these settings can be changed in real time, which means that they take effect immediately after the policy is applied, without requiring a reboot or a reconnection of the Horizon Client. However, some of these settings cannot be changed in real time, which means that they require a reboot or a reconnection of the Horizon Client to take effect.
The effect of changing any VMware Blast policy that cannot be changed in real time is that the Microsoft GPO update rules apply and GPOs are updated manually or by restarting the Horizon Agent. This means that the new policy settings will not be applied until one of the following events occurs:
The Horizon Agent service is restarted on the remote desktop or RDS host. This can be done manually by using the Services console or the command-line tool sc.exe, or automatically by using a scheduled task or a script.
The remote desktop or RDS host is rebooted. This can be done manually by using the Restart option in Windows, or automatically by using a scheduled task or a script.
The Group Policy refresh interval is reached. This is a configurable time interval that determines how often the system checks for and applies new or changed GPOs. By default, this interval is 90 minutes for domain members and 5 minutes for domain controllers, with a random offset of 0 to 30 minutes. This interval can be modified by using the Group Policy refresh interval for computers setting in the Computer Configuration\Administrative Templates\System\Group Policy folder of the Group Policy Management Console.
Therefore, to ensure that the VMware Blast policy settings that cannot be changed in real time are applied as soon as possible, it is recommended to restart the Horizon Agent service or reboot the remote desktop or RDS host after applying the policy.
References: VMware Blast Policy Settings, Group Policy refresh intervals, and [VMware Horizon 8.x Professional Course]
