This MS-900 practice question tests your understanding of describe cloud concepts. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 deploys a custom application on a cloud platform where they manage the operating system and runtime environment, but the cloud provider manages the underlying physical infrastructure, storage, and networking. Which cloud service model is being used?
In IaaS, the customer has control over the operating system, storage, and deployed applications, while the provider manages the underlying infrastructure.
B
Platform as a Service (PaaS)
Why wrong: In PaaS, the provider manages the operating system and runtime; the customer only manages the application and data.
C
Software as a Service (SaaS)
Why wrong: In SaaS, the provider manages everything, and the customer only uses the application.
D
Function as a Service (FaaS)
Why wrong: FaaS is a serverless compute model where customers deploy functions without managing any underlying infrastructure or OS.
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)
The scenario describes a model where the customer manages the operating system and runtime environment, while the cloud provider handles the physical infrastructure, storage, and networking. This aligns precisely with Infrastructure as a Service (IaaS), as IaaS provides virtualized computing resources (e.g., virtual machines) where the customer retains control over the OS, middleware, and applications, but the provider manages the underlying hardware, hypervisor, and physical network.
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 this is correct
In IaaS, the customer has control over the operating system, storage, and deployed applications, while the provider manages the underlying infrastructure.
Related concept
Read the scenario before looking for a memorised answer.
✗
Platform as a Service (PaaS)
Why it's wrong here
In PaaS, the provider manages the operating system and runtime; the customer only manages the application and data.
✗
Software as a Service (SaaS)
Why it's wrong here
In SaaS, the provider manages everything, and the customer only uses the application.
✗
Function as a Service (FaaS)
Why it's wrong here
FaaS is a serverless compute model where customers deploy functions without managing any underlying infrastructure or OS.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse IaaS with PaaS because both involve deploying applications, but the key differentiator is who manages the OS and runtime—IaaS gives the customer full control over these layers, whereas PaaS abstracts them away entirely.
Detailed technical explanation
How to think about this question
Under the hood, IaaS relies on hypervisors (e.g., VMware ESXi, Microsoft Hyper-V) to abstract physical hardware into virtual machines (VMs). The customer interacts with these VMs via remote desktop protocols (e.g., RDP) or SSH, and can configure the OS, install patches, and manage runtime dependencies (e.g., .NET Framework, Java JRE). A real-world scenario is migrating an on-premises legacy application to Azure VMs, where the company retains full control over the OS and runtime to ensure compatibility, while Azure manages the physical servers, storage (e.g., Azure Blob Storage), and virtual networking (e.g., Azure VNet).
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: Infrastructure as a Service (IaaS) — The scenario describes a model where the customer manages the operating system and runtime environment, while the cloud provider handles the physical infrastructure, storage, and networking. This aligns precisely with Infrastructure as a Service (IaaS), as IaaS provides virtualized computing resources (e.g., virtual machines) where the customer retains control over the OS, middleware, and applications, but the provider manages the underlying hardware, hypervisor, and physical network.
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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