MS-900 Describe cloud concepts Practice Question
A company uses a cloud service that provides virtual machines. The company manages the operating system, middleware, and applications, while the cloud provider manages the physical hardware, networking, and data center security. Which cloud service model does this represent?
⚠ Common exam trap
Watch out — candidates often confuse IaaS with PaaS because both involve virtual machines, but PaaS abstracts the OS and middleware, so the key differentiator is who manages the operating system and middleware—if the customer manages them, it is IaaS.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Infrastructure as a Service (IaaS)
This scenario describes Infrastructure as a Service (IaaS) because the customer manages the operating system, middleware, and applications, while the cloud provider is responsible for the physical hardware, networking, and data center security. In IaaS, the provider delivers virtualized computing resources over the internet, and the customer retains control over the guest OS, storage, and deployed applications, which matches the division of responsibilities given.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
IaaS (Infrastructure as a Service) delivers virtualized compute resources as ready-to-use VMs, and the customer retains full control over the guest operating system, runtime, and application stack. The cloud provider is responsible for the physical hosts, the hypervisor, and the data-center networking, while the customer patches, configures, and secures the OS. In this scenario, the company is using a cloud service that provides virtual machines, which directly matches the IaaS delivery model.
- ✗
Platform as a Service (PaaS)
Why it's wrong here
PaaS (Platform as a Service) abstracts away both the underlying infrastructure and the operating system, offering a managed runtime environment, middleware, and development services. The customer only writes and deploys application code; they cannot install a custom OS or manage VMs because the provider automatically handles those layers. Since the scenario explicitly involves virtual machines that the company uses directly, PaaS does not fit — the VM would be entirely managed by the provider.
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Software as a Service (SaaS)
Why it's wrong here
SaaS (Software as a Service) provides a complete, ready-to-use application that is accessed over the internet, such as Microsoft 365 or Salesforce. The customer does not deploy any compute resources or virtual machines; they simply sign in and use the software, with all underlying infrastructure, OS, and applications fully operated by the vendor. This is fundamentally different from a cloud service that provides virtual machines for the company to use directly.
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Desktop as a Service (DaaS)
Why it's wrong here
DaaS (Desktop as a Service) is a specialized offering that delivers virtual Windows desktops and applications to end users through remote display protocols. Although it runs on VMs, its purpose is to replace local desktop environments — not to give customers general-purpose VMs for running custom workloads. The company uses VMs as compute resources, so DaaS, which is scoped to desktop virtualization and user profiles, does not apply.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MS-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MS-900 exam.