A company runs a custom application on a cloud provider's infrastructure. The provider manages the physical servers, networking, and storage, but the company installs, configures, and patches the operating system and application. Which cloud service model is this?
IaaS provides virtualized compute, storage, and networking as raw infrastructure blocks, with the provider maintaining only the physical data center, hosts, hypervisor, and network fabric. The customer provisions virtual machines, installs and patches the guest operating system, configures storage and firewall rules, and runs the custom application on top. In the scenario, the customer has control over the OS and app stack, which is exactly the IaaS responsibility model.
Why this answer
This scenario describes Infrastructure as a Service (IaaS) because the cloud provider manages the underlying physical infrastructure (servers, networking, storage), while the customer retains control over the operating system, middleware, and application. In IaaS, the customer is responsible for OS patching, configuration, and application management, which matches the given responsibilities.
How to eliminate wrong answers
Option A is wrong because Software as a Service (SaaS) delivers a fully managed application to end users, where the provider handles everything including the OS and application, and the customer does not install or patch the OS. Option B is wrong because Platform as a Service (PaaS) provides a managed runtime environment where the provider manages the OS and middleware, and the customer only deploys code, not the OS or its patches. Option D is wrong because Function as a Service (FaaS) is an event-driven compute model where the provider manages the entire infrastructure and the customer only uploads individual functions, with no OS-level access or patching responsibility.