Which statement about cloud service models is most accurate?

• A. Platform-as-a-Service
• B. Software-as-a-Service
• C. Infrastructure-as-a-Service
• D. Network-as-a-Service

Answer: (B)

Software-as-a-Service is the model where the application is hosted by a provider and accessed over the internet. The provider handles the underlying infrastructure, platform, and the software itself, so you can use the application without installing or maintaining it on your own devices. Updates, security, and scaling are managed by the vendor, and you typically pay per user or per usage. This makes it the clearest description of cloud service models when talking about software delivered as a service rather than something you build or manage yourself.

Platform-as-a-Service offers a ready-made environment for developers to build, test, and deploy applications without worrying about the underlying hardware or operating systems. Infrastructure-as-a-Service provides raw computing resources—virtual machines, storage, and networks—where you install and manage your own software. Network-as-a-Service focuses on delivering networking capabilities over the cloud. In that sense, SaaS best encapsulates the idea of software provided as a service to end users.