The answer is Platform as a Service (PaaS). This is the correct choice because PaaS abstracts away the underlying infrastructure, providing a fully managed hosting environment where you simply upload your code and the cloud provider handles the runtime, operating system, scaling, and load balancing—exactly what a startup needs to avoid purchasing or managing servers. On the Microsoft Azure Fundamentals AZ-900 exam, this scenario tests your ability to distinguish between the three cloud service models: IaaS gives you virtual machines to manage, SaaS delivers ready-to-use software, and PaaS sits in the middle as a platform for developers. A common trap is confusing PaaS with IaaS, but remember that if you don’t have to manage the OS or runtime, it’s PaaS. For a memory tip, think of PaaS as “Platform as a Service” where you bring your code and the platform does the rest—like Azure App Service, which handles automatic scaling and patching so you can focus purely on development.
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 wants to run a web application without purchasing or managing any servers. They only want to upload their code and let the cloud provider handle everything from the runtime to scaling. 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.
Why wrong: IaaS provides virtual machines and storage, but customers must manage the OS, patches, and configurations.
B
Platform as a Service (PaaS)
PaaS offers a managed hosting environment where you deploy your code and the provider handles servers, runtime, and scaling. Examples: Azure App Service.
C
Software as a Service (SaaS)
Why wrong: SaaS provides ready-to-use software applications (e.g., Office 365). Customers do not upload custom code.
D
Function as a Service (FaaS)
Why wrong: FaaS is a subset of PaaS for event-driven, serverless functions (e.g., Azure Functions). While it fits, the scenario mentions a web application, which is more commonly associated with PaaS like App Service.
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 provides a fully managed hosting environment where the startup can deploy their web application code without needing to provision or manage underlying servers, operating systems, or runtime infrastructure. Azure App Service is a prime example of PaaS that handles automatic scaling, load balancing, and patching, allowing developers to focus solely on code.
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 and storage, but customers must manage the OS, patches, and configurations.
✓
Platform as a Service (PaaS)
Why this is correct
PaaS offers a managed hosting environment where you deploy your code and the provider handles servers, runtime, and scaling. Examples: Azure App Service.
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 software applications (e.g., Office 365). Customers do not upload custom code.
✗
Function as a Service (FaaS)
Why it's wrong here
FaaS is a subset of PaaS for event-driven, serverless functions (e.g., Azure Functions). While it fits, the scenario mentions a web application, which is more commonly associated with PaaS like App Service.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse FaaS with PaaS because both are serverless, but FaaS is for individual functions triggered by events, not for hosting a complete web application with a persistent runtime.
Trap categories for this question
Scenario analysis trap
FaaS is a subset of PaaS for event-driven, serverless functions (e.g., Azure Functions). While it fits, the scenario mentions a web application, which is more commonly associated with PaaS like App Service.
Detailed technical explanation
How to think about this question
Under the hood, PaaS abstracts the entire infrastructure layer, including the hypervisor, OS, runtime (e.g., .NET, Node.js, Python), and web server (e.g., IIS, Kestrel). Azure App Service automatically handles scaling by adding or removing worker instances based on HTTP request load, using a built-in load balancer and autoscale rules defined by metrics like CPU or memory usage. A subtle behavior is that while PaaS manages the runtime, the developer is still responsible for application-level configuration, such as connection strings and environment variables, which are injected via app settings.
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 AZ-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) is the correct model because it provides a fully managed hosting environment where the startup can deploy their web application code without needing to provision or manage underlying servers, operating systems, or runtime infrastructure. Azure App Service is a prime example of PaaS that handles automatic scaling, load balancing, and patching, allowing developers to focus solely on code.
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.
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Variation 1. A startup wants to run a web application without managing the underlying servers. They only want to upload their code and let the cloud provider handle the runtime, scaling, and maintenance. Which cloud service model is this?
easy
✓ A.Platform as a Service (PaaS)
B.Infrastructure as a Service (IaaS)
C.Software as a Service (SaaS)
D.Function as a Service (FaaS)
Why A: Platform as a Service (PaaS) is the correct model because it provides a managed hosting environment where the startup can deploy their web application code without managing the underlying servers, operating systems, or runtime infrastructure. Azure App Service is a prime example of PaaS, handling automatic scaling, patching, and load balancing while the customer only focuses on code and data.
Last reviewed: Jun 11, 2026
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