- A
Azure App Service
Azure App Service can run containerized web applications and supports automatic scaling (horizontal scale) based on metrics like HTTP request rate or CPU utilization, without requiring any administrator to manage underlying VMs or orchestration pieces.
- B
Azure Container Instances (ACI)
Why wrong: Azure Container Instances provides a simple way to run a container, but it does not have built-in autoscaling based on traffic load. Scaling multiple container groups must be implemented separately, often requiring external logic or additional services.
- C
Azure Kubernetes Service (AKS)
Why wrong: Azure Kubernetes Service offers powerful container orchestration and can autoscale pods and nodes, but it still involves managing the Kubernetes cluster's infrastructure and configuration. The company wants to avoid any infrastructure management, making AKS more complex than needed for this scenario.
- D
Azure Functions
Why wrong: Azure Functions is a serverless compute service designed for event-driven, short-lived functions. It is not intended for hosting long-running containerized web applications, and its scaling model is based on function executions rather than HTTP traffic to a persistent application.
Quick Answer
The answer is Azure App Service, which is the correct choice because it natively supports containerized web applications with built-in autoscaling for containers, automatically adjusting the number of running instances based on metrics like CPU or memory thresholds during traffic spikes. This platform handles the underlying infrastructure, patching, and load balancing, so you never need to manage servers manually—ideal for variable patterns like lunch-hour surges. On the AZ-900 exam, this scenario tests your understanding of Platform as a Service (PaaS) versus Infrastructure as a Service (IaaS); a common trap is selecting Azure Container Instances, which lacks built-in autoscaling, or Azure Kubernetes Service, which requires more manual cluster management. Remember the memory tip: “App Service auto-scales containers without containers of complexity”—if the question emphasizes zero server management and automatic scaling, think App Service first.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. 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 company plans to containerize a legacy web application and run it on Azure. The application experiences variable traffic volumes, with periodic spikes during lunch hours and weekends. The company wants the solution to automatically increase the number of running container instances during high demand and reduce them during low demand, without requiring any manual intervention or management of server infrastructure. Which Azure compute service should the company use?
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
Azure App Service
Azure App Service is correct because it supports containerized web applications with built-in autoscaling capabilities that automatically adjust the number of running container instances based on demand, such as CPU or memory thresholds, without requiring any manual intervention or server management. The platform handles the underlying infrastructure, patching, and load balancing, making it ideal for variable traffic patterns like lunch-hour spikes.
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.
- ✓
Azure App Service
Why this is correct
Azure App Service can run containerized web applications and supports automatic scaling (horizontal scale) based on metrics like HTTP request rate or CPU utilization, without requiring any administrator to manage underlying VMs or orchestration pieces.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Azure Container Instances (ACI)
Why it's wrong here
Azure Container Instances provides a simple way to run a container, but it does not have built-in autoscaling based on traffic load. Scaling multiple container groups must be implemented separately, often requiring external logic or additional services.
- ✗
Azure Kubernetes Service (AKS)
Why it's wrong here
Azure Kubernetes Service offers powerful container orchestration and can autoscale pods and nodes, but it still involves managing the Kubernetes cluster's infrastructure and configuration. The company wants to avoid any infrastructure management, making AKS more complex than needed for this scenario.
- ✗
Azure Functions
Why it's wrong here
Azure Functions is a serverless compute service designed for event-driven, short-lived functions. It is not intended for hosting long-running containerized web applications, and its scaling model is based on function executions rather than HTTP traffic to a persistent application.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure Container Instances (ACI) as the go-to for containerized apps, but ACI lacks native autoscaling and is better suited for burstable, short-lived tasks, while Azure App Service provides the required autoscaling and serverless management for containerized web applications with variable traffic.
Trap categories for this question
Scenario analysis trap
Azure Kubernetes Service offers powerful container orchestration and can autoscale pods and nodes, but it still involves managing the Kubernetes cluster's infrastructure and configuration. The company wants to avoid any infrastructure management, making AKS more complex than needed for this scenario.
Detailed technical explanation
How to think about this question
Azure App Service uses the Web Apps feature to run containers via the 'Web App for Containers' option, leveraging the built-in autoscale engine that scales out based on metrics like CPU percentage, memory percentage, or HTTP queue length, with scale rules defined in the Azure portal or ARM templates. Under the hood, App Service uses a front-end load balancer and a scale controller that monitors these metrics and adjusts the number of instances across fault domains, ensuring high availability during traffic spikes without requiring any Kubernetes or container orchestration knowledge.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this AZ-900 question test?
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure App Service — Azure App Service is correct because it supports containerized web applications with built-in autoscaling capabilities that automatically adjust the number of running container instances based on demand, such as CPU or memory thresholds, without requiring any manual intervention or server management. The platform handles the underlying infrastructure, patching, and load balancing, making it ideal for variable traffic patterns like lunch-hour spikes.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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.
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