Which of the following is NOT a form of desktop virtualization?

Desktop virtualization refers to various technologies that allow users to access a desktop environment remotely or run multiple desktops on a single physical machine. The first three options—Virtual Desktop Infrastructure, Remote Desktop Services, and Desktop-As-A-Service—are all methods of enabling desktop virtualization, providing users with virtualized desktop environments that can be accessed from various devices.

In contrast, server consolidation focuses on optimizing server resources by consolidating multiple server instances onto fewer physical servers. This practice is aimed at increasing efficiency, reducing costs, and maximizing resource utilization, but it does not specifically pertain to the virtualization of desktop environments. Therefore, this option stands apart as not being a form of desktop virtualization, making it the correct answer to the question.