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 development team wants to build a custom web application. They choose a cloud service that provides the runtime environment, operating system, and middleware, but the team is responsible for writing and deploying their own code. The provider automatically applies patches to the underlying infrastructure. Which cloud service model best describes this approach?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Platform as a Service (PaaS)
Platform as a Service (PaaS) provides the runtime environment, operating system, and middleware, allowing developers to focus on writing and deploying their own code while the cloud provider manages the underlying infrastructure, including automatic patching. This model abstracts the hardware and OS layer, giving the team full control over application code but not the platform stack.
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 offers virtual machines and storage, but the customer must manage the operating system and middleware patching.
✓
Platform as a Service (PaaS)
Why this is correct
Correct. PaaS provides the platform infrastructure (runtime, OS, middleware) and manages it, allowing the team to focus on code deployment.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Software as a Service (SaaS)
Why it's wrong here
Incorrect. SaaS delivers complete applications over the internet; the customer does not deploy custom code.
✗
Function as a Service (FaaS)
Why it's wrong here
Incorrect. FaaS is serverless compute but does not provide a full platform for custom web applications with middleware.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse IaaS with PaaS because both involve deploying custom code, but IaaS requires the team to manage the OS and middleware patching, whereas PaaS automates that responsibility.
Detailed technical explanation
How to think about this question
In PaaS, the provider typically uses containerization (e.g., Docker) or managed runtimes (e.g., Azure App Service) to isolate applications while handling OS patching via automated update mechanisms like Azure Update Manager. A real-world scenario is deploying a Node.js web app on Azure App Service: the team writes code, but Microsoft patches the underlying Windows Server or Linux VM, applies security updates to the IIS or Nginx middleware, and manages the runtime (e.g., Node.js version) via platform updates.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Platform as a Service (PaaS) — Platform as a Service (PaaS) provides the runtime environment, operating system, and middleware, allowing developers to focus on writing and deploying their own code while the cloud provider manages the underlying infrastructure, including automatic patching. This model abstracts the hardware and OS layer, giving the team full control over application code but not the platform stack.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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