What model involves hosting all desktop instances on a single server or server farm?

The centralized model involves hosting all desktop instances on a single server or server farm, allowing multiple users to access their desktop environments from any compatible device. This setup streamlines management, as administrators can maintain and update the operating system, applications, and data in one location rather than on individual machines. It enhances security and compliance since sensitive data can be securely stored on the server rather than on local devices, reducing the risk of data loss or unauthorized access.

In a centralized environment, users typically connect to virtual desktops or applications through remote access protocols, allowing for a consistent user experience regardless of the device used. This model also facilitates easier scaling of resources, as additional computing power can be provisioned on the server side without individual hardware upgrades at each user's workstation.

By contrast, the decentralized model distributes the hosting of desktop instances across various individual machines, which can complicate management and security. The distributed model spreads workloads across multiple servers or devices, rather than centralizing them. Lastly, the hybrid model combines elements of both centralized and decentralized approaches, not fitting the description of hosting all instances on a single server or farm.