Which of the following best describes IaaS (Infrastructure as a Service)?

• A. PaaS offers a managed runtime and platform; customer manages applications and data; provider handles runtime, middleware, OS, and virtualization.
• B. IaaS provides virtualized hardware; customer manages OS, apps, and data; provider manages hardware, virtualization, networking, and storage.
• C. A service model where customers rent software licenses and manage configuration.
• D. SaaS delivers software over the internet; customer uses the application and configures data; provider handles nearly everything including security.

Answer: (B)

Infrastructure as a Service gives you virtualized hardware resources over the network. The provider supplies the underlying physical hardware, the virtualization layer, networking, and storage. You, in turn, manage the operating system, applications, and data that run on that hardware. This separation lets you deploy and scale servers quickly without owning the hardware, while retaining control of the software stack.

That separation is what makes this option the best fit for IaaS. It describes the provider handling the hardware and virtualization, with the customer responsible for the OS, apps, and data. Descriptions that place the provider in charge of runtime and middleware point to a platform-style service (PaaS). Descriptions focused on software licensing or on delivering software over the internet with the provider handling most of the stack align with SaaS.