MS-900 Describe cloud concepts Practice Question
A development team uses a cloud service to run applications where the provider manages the runtime environment, operating system, and middleware. The team only writes and uploads code. Which service model are they using?
⚠ Common exam trap
Candidates often confuse PaaS with IaaS because both involve deploying applications, but the key differentiator is who manages the runtime and middleware — PaaS abstracts them away, while IaaS requires the user to manage them.
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
✓
PaaS (Platform as a Service)
The scenario describes the team writing and uploading code while the provider manages the runtime environment, operating system, and middleware. This is the defining characteristic of Platform as a Service (PaaS), where the cloud provider abstracts the underlying infrastructure and platform layers, allowing developers to focus solely on application code. In PaaS, the provider handles OS patching, runtime updates, and middleware configuration, which matches the description exactly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
IaaS (Infrastructure as a Service)
Why it's wrong here
With IaaS, the cloud provider supplies virtualized compute, storage, and networking, but the development team remains responsible for patching the operating system, installing middleware and runtimes, and maintaining the entire application stack. Because the scenario requires simply running applications without managing infrastructure, IaaS would demand significant operational overhead and does not match the described need.
- ✓
PaaS (Platform as a Service)
Why this is correct
PaaS provides a managed hosting environment in which the provider handles the operating system, runtime, middleware, and underlying hardware, allowing developers to focus exclusively on writing and deploying application code. This directly fits a development team that wants to run applications in the cloud without provisioning or maintaining servers, while still having full control over their code and configuration.
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SaaS (Software as a Service)
Why it's wrong here
SaaS delivers fully functional, ready-to-use software over the internet, with the provider managing everything from the infrastructure to the application itself, so users simply consume the product rather than deploy custom code. A development team tasked with running its own applications would not benefit from SaaS, since they would be restricted to the features and interfaces provided by the vendor and would not have a platform to execute their own application logic.
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FaaS (Function as a Service)
Why it's wrong here
FaaS, or serverless functions, executes discrete, event-driven code snippets that are stateless and typically short-lived, with the provider automatically scaling the underlying runtime for each invocation. Although the provider manages the execution environment, FaaS is not suited for running a full application with a persistent process or stateful runtime, which is what the scenario implies when a team wants to run applications as a whole.
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