- A
Infrastructure as a Service (IaaS)
Why wrong: IaaS provides virtual machines, storage, and networks. The customer is responsible for managing the operating system, middleware, and runtime. This still requires maintenance effort.
- B
Platform as a Service (PaaS)
PaaS abstracts the underlying infrastructure. The customer deploys application code and the cloud provider manages the platform, including scaling, patching, and availability. This allows the team to focus on development.
- C
Software as a Service (SaaS)
Why wrong: SaaS provides ready-to-use applications like Office 365. The customer does not write code; they use the software. This does not fit building a custom mobile app backend.
- D
Function as a Service (FaaS)
Why wrong: FaaS (e.g., Azure Functions) allows running small pieces of code in response to events. While it abstracts infrastructure, it is typically used for microservices or event-driven scenarios, not for a full backend application that might need a persistent server. The scenario describes a broader mobile app backend, which is better served by PaaS.
Quick Answer
The answer is Platform as a Service (PaaS). PaaS is the correct choice because it abstracts the underlying infrastructure—servers, operating systems, and scaling—so developers can focus entirely on writing code and deploying features without managing patches or capacity. On the Microsoft Azure Fundamentals AZ-900 exam, this scenario tests your ability to differentiate cloud service models by their level of abstraction; a common trap is confusing PaaS with IaaS, where you still handle OS patches and scaling. Remember that PaaS gives you a fully managed runtime environment, while SaaS delivers ready-to-use software and IaaS leaves you in charge of the virtual machines. For the exam, think of PaaS as “platform, not plumbing”—you bring your code, Azure handles the rest. A useful memory tip: PaaS = “Paste and run,” IaaS = “I assemble the stack,” and SaaS = “Subscribe and use.”
AZ-900 Describe cloud concepts Practice Question
This AZ-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 startup is building a mobile app backend and wants to use cloud services. They want to focus entirely on writing code and deploying features without worrying about server maintenance, operating system patches, or scaling infrastructure. Which cloud service model best fits this requirement?
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 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
Platform as a Service (PaaS)
Platform as a Service (PaaS) is the correct model because it abstracts the underlying infrastructure, including servers, operating systems, and scaling, allowing developers to focus solely on writing code and deploying features. Azure App Service is a prime example of PaaS, providing built-in load balancing, auto-scaling, and patching without developer intervention.
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
IaaS provides virtual machines, storage, and networks. The customer is responsible for managing the operating system, middleware, and runtime. This still requires maintenance effort.
- ✓
Platform as a Service (PaaS)
Why this is correct
PaaS abstracts the underlying infrastructure. The customer deploys application code and the cloud provider manages the platform, including scaling, patching, and availability. This allows the team to focus on development.
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
SaaS provides ready-to-use applications like Office 365. The customer does not write code; they use the software. This does not fit building a custom mobile app backend.
- ✗
Function as a Service (FaaS)
Why it's wrong here
FaaS (e.g., Azure Functions) allows running small pieces of code in response to events. While it abstracts infrastructure, it is typically used for microservices or event-driven scenarios, not for a full backend application that might need a persistent server. The scenario describes a broader mobile app backend, which is better served by PaaS.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse FaaS (serverless) with PaaS, but the AZ-900 exam tests the core NIST service models (IaaS, PaaS, SaaS) where FaaS is considered a subset of PaaS or a serverless compute option, not a primary model; the question explicitly asks for the 'best fit' among the listed options, and PaaS directly addresses the full requirement of focusing on code and deployment without infrastructure management.
Trap categories for this question
Scenario analysis trap
FaaS (e.g., Azure Functions) allows running small pieces of code in response to events. While it abstracts infrastructure, it is typically used for microservices or event-driven scenarios, not for a full backend application that might need a persistent server. The scenario describes a broader mobile app backend, which is better served by PaaS.
Detailed technical explanation
How to think about this question
Under the hood, PaaS platforms like Azure App Service manage the runtime environment, including the web server (e.g., IIS), language runtime (e.g., .NET, Node.js), and middleware, while automatically handling OS patches via Azure Update Management. A real-world scenario: a startup deploying a Node.js API on Azure App Service can push code via Git, and the platform automatically scales out to multiple instances under load using Azure Autoscale, without the developer ever touching a VM or configuring a load balancer.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Describe cloud concepts — study guide chapter
Learn the concepts, then practise the questions
- →
Describe cloud concepts practice questions
Targeted practice on this topic area only
- →
All AZ-900 questions
1,031 questions across all exam domains
- →
Microsoft Azure Fundamentals AZ-900 study guide
Full concept coverage aligned to exam objectives
- →
AZ-900 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related AZ-900 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Describe cloud concepts practice questions
Practise AZ-900 questions linked to Describe cloud concepts.
Describe Azure architecture and services practice questions
Practise AZ-900 questions linked to Describe Azure architecture and services.
Describe Azure management and governance practice questions
Practise AZ-900 questions linked to Describe Azure management and governance.
AZ-900 Azure services practice questions
Practise AZ-900 questions linked to AZ-900 Azure services.
AZ-900 pricing and support practice questions
Practise AZ-900 questions linked to AZ-900 pricing and support.
AZ-900 security and compliance practice questions
Practise AZ-900 questions linked to AZ-900 security and compliance.
AZ-900 governance practice questions
Practise AZ-900 questions linked to AZ-900 governance.
Practice this exam
Start a free AZ-900 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this AZ-900 question test?
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) is the correct model because it abstracts the underlying infrastructure, including servers, operating systems, and scaling, allowing developers to focus solely on writing code and deploying features. Azure App Service is a prime example of PaaS, providing built-in load balancing, auto-scaling, and patching without developer intervention.
What should I do if I get this AZ-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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 11, 2026
This AZ-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 AZ-900 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.