Question 171 of 981
AZ-900 Describe Azure architecture and services Practice Question
Which Azure compute service lets you run containers without managing any virtual machine infrastructure, paying only for CPU and memory used while the container runs?
⚠ Common exam trap
Watch out — candidates often confuse Azure Container Instances with Azure Kubernetes Service, assuming both are 'serverless' container options, but AKS still requires managing node pools and pays for VM infrastructure, whereas ACI is truly serverless with per-second billing.
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 Container Instances
Azure Container Instances (ACI) is a serverless container service that allows you to run containers directly on Azure without provisioning or managing any underlying virtual machines. You are billed per second based on the CPU and memory resources consumed while the container is running, making it ideal for burst or short-lived workloads.
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 Kubernetes Service
Why it's wrong here
Azure Kubernetes Service (AKS) is a fully managed Kubernetes orchestration service, meaning it simplifies deploying, managing, and scaling containerized applications across a cluster. However, AKS requires you to manage the underlying node pool VMs (at least one agent node) that host your containers, and you pay for those VMs on a per-hour basis, even if only a single container is running. It provides rich orchestration features (scaling, load balancing, service discovery) but is not a serverless per-container execution model like ACI, so it is incorrect for this scenario.
- ✗
Azure App Service
Why it's wrong here
Azure App Service is a PaaS service designed primarily for hosting web applications, REST APIs, and mobile backends. While it can run containers via Web App for Containers, it allocates dedicated, continuously running compute resources (App Service plans with fixed VM tiers), and billing is per hour based on the plan size, not per-second per container. It is not a serverless container execution service suited for isolated, ephemeral container workloads.
- ✓
Azure Container Instances
Why this is correct
Azure Container Instances (ACI) is the correct answer because it is a serverless container service that runs containers on-demand without requiring you to provision or manage underlying VMs. You specify CPU and memory requirements, and ACI places the container on shared infrastructure, with billing per-second based on the resources consumed. It is ideal for simple container workloads, event-driven tasks, or burst scenarios where you need immediate, isolated container execution without orchestration overhead.
- ✗
Azure Batch
Why it's wrong here
Azure Batch is a cloud-scale job scheduling and compute management service designed for running large-scale parallel and high-performance computing (HPC) batch jobs. It manages a pool of VMs (nodes) to execute many tasks in parallel, and you pay for the underlying compute nodes while they are allocated. It is not meant for on-demand execution of individual standalone containers; using Batch for a single container would require setting up a pool and scheduling a job, which is far heavier than ACI's instant container startup.
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 |
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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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