In which service model can users start, stop, and configure virtual servers?

The Infrastructure as a Service (IaaS) model allows users to start, stop, and configure virtual servers according to their specific needs. This model provides users with basic computing resources like virtual machines, storage, and networking capabilities, enabling them to have significant control over the operating systems and applications that run on those servers.

Users utilizing IaaS can dynamically allocate or deallocate resources based on demand, making it highly flexible and scalable. They manage the server environment, including installing software and configuring settings, akin to managing physical servers but without the hardware overhead. This level of control is essential for applications that require specific configurations or environments.

In contrast, other service models such as Platform as a Service (PaaS) and Software as a Service (SaaS) offer more restrictive environments where users have limited control over the underlying infrastructure or cannot manage individual virtual machines. PaaS provides a platform for developing applications without dealing with much of the hardware or software environment, while SaaS delivers fully functional software applications over the internet without user management of the underlying infrastructure. Similarly, Storage as a Service is focused solely on storage solutions and does not typically include the ability to manage virtual servers.