MS-900 Describe cloud concepts Practice Question
A user wants to access company email and documents from any device, anywhere. Which cloud model is Microsoft 365?
⚠ Common exam trap
MS-900 often tests the difference between SaaS, PaaS, and IaaS by presenting a familiar product (Microsoft 365) and expecting candidates to recognise that the provider manages everything from the application down — candidates sometimes pick PaaS because they confuse 'cloud-hosted application' with 'platform'.
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
✓
Software as a Service (SaaS)
Microsoft 365 is a SaaS offering because Microsoft hosts and manages the applications (Exchange Online, SharePoint Online, Teams, Office apps) and the underlying infrastructure, and customers access them over the internet via subscription. Users consume the software without managing servers, patching, or platform configuration. This matches the SaaS model where the provider delivers a complete, ready-to-use application.
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) provides an application-hosting environment: compute, middleware, and development tools for building and deploying custom software. It does not include ready-to-use productivity applications, so a non-technical user cannot simply sign in to get company email or shared documents. Choosing PaaS would require an IT team to develop and operate a custom email/document solution on top of it, which is not what the user is asking for.
- ✓
Software as a Service (SaaS)
Why this is correct
Software as a Service (SaaS) delivers fully managed applications over the internet through a subscription. Microsoft 365 is the canonical example: Exchange Online hosts company mailboxes, and SharePoint Online/OneDrive host documents, all accessible from any device through a browser or Office client without manual patching or server maintenance. This directly matches the user’s requirement for ready-to-use email and document access from anywhere.
- ✗
Infrastructure as a Service (IaaS)
Why it's wrong here
Infrastructure as a Service (IaaS) rents fundamental resources—virtual CPUs, memory, storage, and networking—in a self-managed model. It would provide raw virtual machines to build on, but none of the email or document collaboration functionality is included; you would have to install, secure, patch, and operate an email server and file server yourself. That contradicts the intent of a user who simply wants to reach existing company email and documents from any location.
- ✗
Desktop as a Service (DaaS)
Why it's wrong here
Desktop as a Service (DaaS) streams a full virtual desktop environment to end users, commonly using Windows 365 or Azure Virtual Desktop with remote protocols such as RDP. Although Office applications could run inside that desktop, DaaS itself does not provide the underlying mailboxes or document libraries; those would still need to be provisioned separately, and the user would be tied to a desktop session instead of getting direct, app-level access to email and files.
Go deeper
Related to this question
Learn chapter
Exchange Online Protection (EOP)
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.
Key term
Subscription
A subscription is a payment model where you pay a recurring fee to access a product or service instead of buying it once and owning it forever.
About these practice questions
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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.