This MS-900 practice question tests your understanding of describe cloud concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company wants to use a cloud service that provides ready-to-use business applications such as email, collaboration, and customer relationship management without managing the underlying infrastructure. Which cloud service model is this?
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)
Option C (SaaS) is correct because Software as a Service delivers ready-to-use business applications like Microsoft 365 (Exchange Online for email, Teams for collaboration, Dynamics 365 for CRM) over the internet, with the provider managing all underlying infrastructure, including servers, storage, and networking. The customer simply accesses the software via a web browser or client app without any responsibility for patching, scaling, or hardware maintenance.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 it's wrong here
Incorrect. IaaS provides virtual machines and storage, not pre-built applications.
✗
Platform as a Service (PaaS)
Why it's wrong here
Incorrect. PaaS is a platform for developing and deploying custom apps, not ready-to-use business applications.
✓
Software as a Service (SaaS)
Why this is correct
Correct. SaaS delivers applications like email (Exchange Online) and CRM (Dynamics 365) that are managed completely by the provider.
Related concept
Read the scenario before looking for a memorised answer.
✗
Private cloud
Why it's wrong here
Incorrect. Private cloud is a deployment model where resources are dedicated to one organization, not a service model.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse PaaS with SaaS because both abstract infrastructure, but PaaS requires the customer to develop and manage the application code, whereas SaaS provides fully functional, ready-to-use applications—a distinction Microsoft emphasizes in the MS-900 by focusing on the 'what you manage' vs. 'what the provider manages' model.
Detailed technical explanation
How to think about this question
Under the hood, SaaS applications are multi-tenant, meaning a single instance of the software serves multiple customers, with data isolation enforced at the application layer (e.g., through tenant IDs in database queries). In Microsoft 365, Exchange Online uses a shared mailbox database model with role-based access control (RBAC) and tenant boundaries enforced by Azure Active Directory. A real-world scenario: a company using Dynamics 365 for CRM benefits from automatic updates, built-in compliance (e.g., ISO 27001), and global redundancy without ever touching the underlying Hyper-V hosts or SQL Server clusters.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-900 question in full detail.
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Software as a Service (SaaS) — Option C (SaaS) is correct because Software as a Service delivers ready-to-use business applications like Microsoft 365 (Exchange Online for email, Teams for collaboration, Dynamics 365 for CRM) over the internet, with the provider managing all underlying infrastructure, including servers, storage, and networking. The customer simply accesses the software via a web browser or client app without any responsibility for patching, scaling, or hardware maintenance.
What should I do if I get this MS-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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