The answer is Azure Container Instances, or ACI, because it is the serverless container service that lets you run containers without provisioning or managing any underlying virtual machine infrastructure. This is correct because ACI abstracts away the host VMs entirely, allowing you to deploy a container directly and pay only for the CPU and memory resources consumed while the container runs, on a per-second billing model. On the AZ-900 exam, this question tests your understanding of Azure’s compute options, specifically distinguishing serverless containers from services like Azure Kubernetes Service or Virtual Machines. A common trap is confusing ACI with Azure Container Apps or Azure Batch, but remember: ACI is the simplest, most direct “pay per use” option for running a single container instantly with no orchestration overhead. For a memory tip, think “ACI = A Container Instantly,” emphasizing its immediate, serverless, and consumption-based nature.
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.
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?
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.
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 Kubernetes Service
Why it's wrong here
AKS requires managing node pools (VMs); ACI is truly serverless for individual containers.
✗
Azure App Service
Why it's wrong here
App Service can run containers but allocates dedicated compute resources, not per-second billing for individual containers.
✓
Azure Container Instances
Why this is correct
ACI runs containers without managing VMs, with per-second billing for CPU and memory used.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Batch
Why it's wrong here
Azure Batch is for large-scale parallel compute jobs, not on-demand individual container execution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that 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.
Detailed technical explanation
How to think about this question
Under the hood, ACI uses a hypervisor-level isolation technology similar to Hyper-V containers, ensuring each container instance runs in its own security boundary. The billing model is based on the vCPU count and memory size (in GB) allocated at creation time, with a minimum billing increment of 1 second, which is critical for cost-sensitive, ephemeral tasks like data processing or CI/CD job runners. A real-world scenario is running a one-time image resizing job: you spin up an ACI container, pay only for the 30 seconds it runs, and tear it down automatically.
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.
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 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 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.
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.
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Question Discussion
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