Which type of application does the User Layer support?

The Citrix App Layering User Layer is designed to persist user-profile settings, data, and user-installed applications in a non-persistent VDI environment. Applications that contain add-ins, such as Microsoft Office plug-ins or browser extensions, are a primary use case. These types of applications are typically installed by the user and do not make deep, system-level modifications to the operating system kernel, network stack, or boot process, making them ideal candidates for inclusion in the User Layer.

A. Applications that modify the network stack: These applications (e.g., VPN clients) install low-level drivers that are incompatible with the User Layer and must be installed in the OS or an App Layer.
B. Applications that modify hardware: Applications that install hardware drivers must be included in the OS Layer or Platform Layer, as the User Layer is not designed for hardware-level integration.
C. Applications with boot level drivers: Boot-level drivers load before the user logs in and the User Layer is attached. Therefore, any application requiring them cannot function when installed on a User Layer.

1. Citrix App Layering 4.x Product Documentation, "Deploy user layers": This official documentation explicitly lists what cannot be included in a user layer. It states, "Do not install the following types of applications on a user layer: Applications that modify the network stack or hardware. For example, a VPN client." and "Applications that have boot-level drivers." This directly invalidates options A, B, and C. The documentation confirms the User Layer is for applications a user can install, which includes applications with add-ins. (Reference Section: "What cannot be included in a user layer").