MS-900 Describe cloud concepts Practice Question
A company is evaluating cloud service models for running custom line-of-business applications. They need full control over the operating system and applications, but want to avoid managing physical hardware. Which cloud service model should they choose?
⚠ Common exam trap
MS-900 often tests the shared responsibility boundary by pairing 'full control over OS' with 'no hardware management' — candidates who reflexively pick PaaS because it sounds 'cloud-native' miss that only IaaS grants OS-level control.
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)
IaaS provides virtualized compute, storage, and networking where the customer retains full control over the operating system, middleware, and applications while the provider manages the physical hardware, hypervisor, and datacenter. Because the requirement is 'full control over OS and applications' without managing physical hardware, IaaS is the exact fit — the customer patches the OS and deploys their own line-of-business software on provider-managed VMs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Software as a Service (SaaS)
Why it's wrong here
SaaS delivers finished applications managed entirely by the provider, so tenants cannot control the operating system or install custom line-of-business software. It is tempting because SaaS removes all infrastructure and patching duties, and it would be the right choice when a standard product such as Microsoft 365 already meets the business requirement without modification.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
IaaS supplies virtualised compute, storage and networking while the customer retains control of the guest operating system and installed applications. This satisfies the requirement for full OS and application control without procuring or maintaining physical servers, unlike PaaS or SaaS.
- ✗
Platform as a Service (PaaS)
Why it's wrong here
PaaS abstracts the operating system, so the company cannot control or patch it, contradicting the requirement for full OS control. PaaS fits developers deploying code onto a managed runtime without wanting to administer servers or operating systems themselves.
- ✗
Function as a Service (FaaS)
Why it's wrong here
FaaS runs event-triggered code snippets on a fully managed runtime, so the provider controls the operating system and you cannot install custom OS-level components or long-running line-of-business applications. It is tempting because FaaS suits discrete, stateless functions triggered by events, such as processing an upload or responding to a webhook, where no server management is wanted.
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Same concept, more angles
3 more ways this is tested on MS-900
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses a cloud provider that offers compute power as a service. The provider manages the physical servers, storage, and networking, but the company has full control over the operating system, applications, and configurations. Which cloud service model is being used?
easy- A.Software as a Service (SaaS)
- B.Platform as a Service (PaaS)
- ✓ C.Infrastructure as a Service (IaaS)
- D.Function as a Service (FaaS)
Why C: The scenario describes Infrastructure as a Service (IaaS), where the cloud provider manages the underlying physical infrastructure (servers, storage, networking), but the customer retains full control over the operating system, applications, and configurations. This aligns with the IaaS model as defined by NIST SP 800-145, which provides virtualized computing resources over the internet.
Variation 2. A company wants to reduce hardware maintenance costs by moving to the cloud. They need to maintain full control over the operating system, applications, and security configurations, but do not want to manage physical servers or data center facilities. Which cloud service model should they choose?
easy- A.Software as a Service (SaaS)
- B.Platform as a Service (PaaS)
- ✓ C.Infrastructure as a Service (IaaS)
- D.On-premises
Why C: Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, allowing the company to deploy and manage their own operating systems, applications, and security configurations while offloading the physical hardware and data center management to the cloud provider. This model gives the highest level of control over the software stack without the burden of maintaining physical servers, aligning perfectly with the requirement to reduce hardware maintenance costs while retaining full administrative access.
Variation 3. A company wants to deploy a cloud solution where they have the maximum control over the operating system, installed software, and security configurations, but they do not want to manage physical servers or data center facilities. Which cloud service model best meets this requirement?
medium- ✓ A.Infrastructure as a Service (IaaS)
- B.Platform as a Service (PaaS)
- C.Software as a Service (SaaS)
- D.Hybrid cloud
Why A: Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, giving the customer full administrative control over the operating system, installed software, and security configurations (e.g., firewall rules, patch management) while the cloud provider manages the physical servers, storage, and networking hardware. This model aligns with the requirement for maximum control without managing physical infrastructure.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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.