MS-900 Describe cloud concepts Practice Question
A service owner is comparing Microsoft 365 capabilities and needs to host custom applications on virtual machines while managing the operating system. Cloud concept or benefit best matches this requirement?
⚠ Common exam trap
Many candidates confuse PaaS with IaaS because both involve hosting applications, but PaaS removes OS management responsibility, which is explicitly required in the question.
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)
Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, including virtual machines where the user manages the operating system and can host custom applications. This matches the requirement because the service owner needs full control over the OS and the ability to deploy custom applications without managing physical hardware.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Platform as a Service (PaaS)
Why it's wrong here
Platform as a Service (PaaS) abstracts not only the operating system but also the runtime stack, middleware, and scaling components, leaving the developer to manage just the application and data. In a scenario where a service owner needs to control the operating system and installed applications, PaaS is incorrect because it removes that control and delegates platform administration to the provider. Microsoft 365 also does not fit PaaS, as it is a fully managed application suite rather than a development platform.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
Infrastructure as a Service (IaaS) is the correct answer because it provides virtualized compute resources—such as virtual machines, storage, and networking—while the customer retains responsibility for the operating system, its patches, and the applications deployed on top. This gives a service owner the flexibility to configure the environment like a traditional on-premises data center without purchasing physical hardware. In the Microsoft ecosystem, Azure virtual machines exemplify IaaS, and this model is distinct from PaaS and SaaS because the provider only manages the physical or virtual infrastructure layer, not the OS or application stack.
- ✗
Hybrid cloud
Why it's wrong here
Hybrid cloud is not a service model but rather a deployment model that combines public cloud, private cloud, and on-premises infrastructure to share data and workloads. It describes where the workloads run—such as integrating Microsoft 365 with an on-premises Active Directory—rather than the level of abstraction or management responsibility for compute, storage, and operating systems. Therefore, it cannot be the correct answer to a question about which cloud service model grants the customer control over the OS and applications, and it is mutually exclusive with IaaS in this context.
- ✗
Software as a Service (SaaS)
Why it's wrong here
Software as a Service (SaaS) is incorrect here because it delivers a finished, ready-to-use application that is fully managed by the provider, including the underlying infrastructure, operating system, runtime, and application updates. This is the opposite of IaaS, where the customer manages the OS and applications. While Microsoft 365 itself is a classic example of SaaS, the question's correct action is to identify the model that provides the service owner with infrastructure-level control, which SaaS explicitly does not offer.
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Key term
Microsoft 365
Microsoft 365 is a subscription-based cloud service from Microsoft that combines productivity tools like Office apps with security, device management, and online storage.
Key term
User
A user is any person, system, or device that interacts with an IT service, resource, or identity system, typically authenticated through credentials and authorized to perform specific actions.
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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.