What cloud service model requires the customer to administer the operating system?

The Infrastructure as a Service (IaaS) model requires customers to manage their own operating system, along with managing applications and data. In this model, cloud providers supply virtualized computing resources over the internet, such as virtual machines, storage, and networks. Customers have the flexibility to choose the operating system they want to use and are responsible for all system maintenance activities, including patching, updating, and configuring the operating system as needed.

This level of control allows organizations to install and run any software they need, but it also means they must be knowledgeable about system administration and security to effectively manage their infrastructure.

In contrast, other cloud service models like Software as a Service (SaaS) and Platform as a Service (PaaS) abstract away much of the operational burden from the customer. In SaaS, the provider manages everything related to the software application, while in PaaS, the provider manages the underlying infrastructure and platform aspects, leaving customers to focus on application development without needing to handle the operating system directly. QaaS, though less commonly referenced, generally pertains to a specific area of service related to quality assurance and testing, and has a different focus unrelated to the administration of an operating system.