AZ-900 Describe cloud concepts Practice Question
A company is developing a new web application. The development team wants to deploy the application code without having to manage the underlying virtual machines, operating systems, or runtime environments. They only want to focus on writing code and let the cloud provider handle the infrastructure, platform, and scaling automatically. Which cloud service model does this scenario describe?
⚠ Common exam trap
Candidates often confuse PaaS with IaaS because both involve deploying applications, but IaaS requires managing the OS and runtime, while PaaS abstracts them entirely—a distinction Microsoft emphasizes by highlighting 'no OS management' as the key differentiator.
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)
This scenario describes Platform as a Service (PaaS) because the development team wants to deploy application code without managing the underlying virtual machines, operating systems, or runtime environments. PaaS provides a managed hosting environment where the cloud provider handles infrastructure, platform updates, and automatic scaling, allowing developers to focus solely on writing and deploying code. In contrast, IaaS would require managing VMs and OS, while SaaS delivers fully built applications, not a platform for custom code deployment.
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
In IaaS, the cloud provider supplies virtualized computing resources (e.g., virtual machines), but the customer is responsible for managing the operating system, runtime, and applications. This does not meet the requirement of avoiding infrastructure management.
When this WOULD be correct
A scenario where the development team needs to deploy and manage their own virtual machines, including installing and configuring the operating system and runtime environment, and they require full control over the infrastructure without abstraction.
- ✓
Platform as a Service (PaaS)
Why this is correct
PaaS, such as Azure App Service, provides a fully managed hosting environment where the cloud provider handles the underlying virtual machines, operating system, middleware, and runtime. Developers simply upload or deploy their code, and the platform automatically provisions the necessary resources, applies security patches, and can scale the application based on demand. This directly matches the team's requirement to deploy a complete web application without managing any server infrastructure or operational overhead.
- ✗
Software as a Service (SaaS)
Why it's wrong here
SaaS offers complete, ready-to-use software applications over the internet (e.g., Office 365). The customer does not write or deploy code; they simply use the application. Since the team wants to develop and deploy their own code, SaaS is not appropriate.
When this WOULD be correct
A company wants to use a cloud-based email service like Microsoft 365 or Google Workspace without managing the underlying infrastructure or software. The question would specify that users access the application via a web browser and the provider handles everything.
- ✗
Function as a Service (FaaS)
Why it's wrong here
FaaS abstracts only the runtime execution of individual functions triggered by events, not the full application deployment lifecycle. The stem specifies deploying a complete web application without managing any infrastructure, which requires a platform that hosts the entire app stack, such as PaaS. FaaS is tempting because it also eliminates server management, but it is correct only when the workload consists of discrete, event-driven code snippets rather than a persistent web application.
When this WOULD be correct
A question that asks: 'A development team wants to run event-driven code in response to HTTP requests or queue messages, without provisioning or managing servers. Which service model?' would make FaaS correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Platform as a Service (PaaS)Correct answer▾
Why this is correct
PaaS, such as Azure App Service, provides a fully managed hosting environment where the cloud provider handles the underlying virtual machines, operating system, middleware, and runtime. Developers simply upload or deploy their code, and the platform automatically provisions the necessary resources, applies security patches, and can scale the application based on demand. This directly matches the team's requirement to deploy a complete web application without managing any server infrastructure or operational overhead.
✗Infrastructure as a Service (IaaS)Wrong answer — click to see why▾
Why this is wrong here
IaaS provides virtual machines and storage, but the customer still manages the OS, runtime, and scaling. The question specifies the team wants to avoid managing VMs, OS, and runtime, which is not satisfied by IaaS.
★ When this WOULD be the correct answer
A scenario where the development team needs to deploy and manage their own virtual machines, including installing and configuring the operating system and runtime environment, and they require full control over the infrastructure without abstraction.
Why candidates choose this
Candidates may confuse IaaS with PaaS because both involve deploying applications, but IaaS still requires managing the underlying OS and runtime, which the question explicitly states the team wants to avoid.
✗Software as a Service (SaaS)Wrong answer — click to see why▾
Why this is wrong here
SaaS provides ready-to-use software applications, not a platform for deploying custom code. The scenario requires deploying application code, which is not a capability of SaaS.
★ When this WOULD be the correct answer
A company wants to use a cloud-based email service like Microsoft 365 or Google Workspace without managing the underlying infrastructure or software. The question would specify that users access the application via a web browser and the provider handles everything.
Why candidates choose this
Candidates may confuse 'focus on writing code' with using a software application, not realizing that SaaS delivers finished applications, not a development platform.
✗Function as a Service (FaaS)Wrong answer — click to see why▾
Why this is wrong here
FaaS (e.g., Azure Functions) still requires managing individual function triggers and bindings, not a full web application deployment. The scenario describes deploying application code without managing any infrastructure or platform, which is PaaS, not FaaS.
★ When this WOULD be the correct answer
A question that asks: 'A development team wants to run event-driven code in response to HTTP requests or queue messages, without provisioning or managing servers. Which service model?' would make FaaS correct.
Why candidates choose this
Candidates may confuse 'focus on writing code' with serverless computing, but FaaS is for discrete functions, not entire web applications, and still requires some configuration of triggers and scaling settings.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
Go deeper
Related to this question
Learn chapter
What is Cloud Computing?
Key term
SaaS
Software as a Service (SaaS) is a cloud computing model where you use software over the internet without installing it on your own computer.
Key term
PaaS
Platform as a Service (PaaS) is a cloud computing model that provides a managed platform for developers to build, run, and manage applications without dealing with the underlying infrastructure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.