Azure compute summary: VMs, App Service, Functions & containers

One page to sort the compute services the exam keeps asking about — most control to least management — with six questions, AZ-900, 2026 edition.

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Azure compute is where AZ-900 turns vocabulary into choices: given a requirement, name the service. The fast way to keep them straight is a single axis — how much you manage versus how much Microsoft manages — and the diagram above lays the main services out on exactly that ladder, most control at the top, least management at the bottom.

The ladder, top to bottom

Azure Virtual Machines sit at the top. This is infrastructure as a service: you get a full operating system, install what you like, and patch on your own schedule. Maximum control, maximum responsibility. The exam tell is any phrase about controlling or patching the operating system — that is a VM.

Azure App Service sits in the middle. It is a managed platform (PaaS) for hosting web apps and APIs. You deploy your code; Microsoft runs the servers, the OS and the patching. The tell is “host a web app without managing servers.”

Azure Functions sits at the bottom. It is serverless and event-driven: your code runs on a trigger, and you pay per execution with nothing charged while idle. The tell is “runs on an event, pay only when it runs.”

That is the whole spine. Move down the ladder and control drops while convenience and cost-efficiency-for-intermittent-work rise.

The containers side note

Containers are a parallel track for portable, consistent deployments, and the exam tests two by name:

Azure Container Instances (ACI) — run a single container fast, with no cluster to set up. Best for simple or short-lived jobs.
Azure Kubernetes Service (AKS) — orchestrate many containers across a cluster, with automatic scaling and self-healing. The trigger word is “orchestration at scale.”

One container, no cluster → ACI. Many containers, managed at scale → AKS.

Scaling identical VMs

One more service the exam likes: Virtual Machine Scale Sets. When you need a group of identical VMs behind a load balancer that add and remove instances automatically as demand changes, that is Scale Sets — not a single bigger VM, and not App Service.

How to read a compute question

Almost every compute question is a requirement in disguise. Match the phrase to the service:

“full control of the OS / install software / patch yourself” → Virtual Machines
“host a web app, no servers to manage” → App Service
“runs on a trigger, pay per execution” → Functions
“a single container, no cluster” → Container Instances
“orchestrate containers at scale” → Kubernetes Service
“many identical VMs that scale automatically” → Scale Sets

Use the questions below

Answer each one before you reveal the explanation, and when you miss, read past the correct answer to why the other options are wrong — the distractors here are the right-sounding service for the wrong requirement. Getting the match right, not just the name, is what carries into the exam. For the wider picture, see the Azure Architecture & Services domain and the AZ-900 cheat sheet.

A control-versus-convenience ladder of Azure compute services. Azure Virtual Machines sit at the top with the most control and the most management, because you manage the operating system. App Service sits in the middle as a managed platform where you deploy a web app without managing servers. Azure Functions sit at the bottom with the least management, serverless and event-driven, billed per execution. A side note shows containers: Azure Container Instances for a single container and Azure Kubernetes Service for orchestrating containers at scale.

6 free AZ-900 practice questions

Answers and explanations — no email wall

AZ-900 Question 1 of 6

A team needs full control over the operating system, including installing custom software and choosing when to patch. Which Azure compute service fits?

Answer: A — Azure Virtual Machines

Azure Virtual Machines is infrastructure as a service (IaaS): you get a full operating system to configure, install software on, and patch on your own schedule. Why not the others: App Service is a managed platform, so Microsoft handles the OS and you do not control patching. Functions is serverless with no OS to manage at all. Container Instances runs a container image, not a full VM you administer. Pro tip: 'full control over the OS' on the exam almost always means a virtual machine.

AZ-900 Question 2 of 6

You want to host a web app and REST API without provisioning or managing the underlying servers. Which service is the best fit?

Answer: A — Azure App Service

Azure App Service is a platform as a service (PaaS) built to host web apps and APIs — you deploy your code and Microsoft manages the servers, OS and patching. Why not the others: Virtual Machines would make you manage the OS yourself. Functions targets short, event-driven pieces of logic rather than a full hosted web app. Kubernetes Service is for orchestrating containers at scale, which is more than a single web app needs. Pro tip: 'host a web app, no servers to manage' = App Service.

AZ-900 Question 3 of 6

Which description best matches Azure Functions?

Answer: A — A serverless, event-driven service where you pay only when your code runs

Azure Functions is serverless and event-driven: code runs in response to a trigger and you are billed per execution, with nothing charged while idle. Why not the others: administering a full OS describes a virtual machine, not Functions. A managed relational database describes a data service, not a compute one. Being billed for an always-on server is the opposite of the serverless, pay-per-execution model. Pro tip: 'runs on a trigger, pay per execution' = Functions.

AZ-900 Question 4 of 6

You need to run a single container for a short batch job, with no cluster to set up. Which Azure service is the simplest fit?

Answer: A — Azure Container Instances

Azure Container Instances runs a single container quickly, with no orchestrator to provision — ideal for a simple or short-lived container job. Why not the others: Azure Kubernetes Service orchestrates many containers across a cluster, which is more than one short job needs. Virtual Machines would make you manage an OS and install a container runtime yourself. App Service hosts web apps rather than arbitrary one-off containers. Pro tip: single container, no cluster = Container Instances; many containers at scale = AKS.

AZ-900 Question 5 of 6

An application must orchestrate many containers across a cluster, with automatic scaling and self-healing. Which Azure service is designed for this?

Answer: A — Azure Kubernetes Service

Azure Kubernetes Service (AKS) is Microsoft's managed Kubernetes for orchestrating containers at scale — scheduling, scaling and self-healing across a cluster. Why not the others: Container Instances runs individual containers without orchestration. Functions is for event-driven code, not container clusters. App Service hosts web apps rather than managing a container cluster. Pro tip: the word 'orchestration' points straight at AKS.

AZ-900 Question 6 of 6

You already run several identical virtual machines behind a load balancer and want them to add or remove instances automatically as demand changes. Which Azure feature provides this?

Answer: A — Virtual Machine Scale Sets

Virtual Machine Scale Sets let you deploy and manage a group of identical, load-balanced VMs that scale out and in automatically as demand changes. Why not the others: a single larger VM scales up but cannot add more instances automatically. App Service is a different, PaaS hosting model rather than a way to scale your own VMs. Container Instances runs containers, not a managed group of VMs. Pro tip: 'many identical VMs that scale automatically' = Scale Sets.

That is exactly how every question in the course works — answer, explanation, why-not. The real set continues in the practice player: 10 free questions, no sign-up.

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Those 6 questions were the start.

The exam does not test whether you recognise a term — it tests whether you can rule out three plausible answers under time pressure. That is what the explanations above are for, and there are 300 more questions built exactly like them.

Collecting questions yourself

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Answer keys without reasoning
No idea which domain you are weak in

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300 questions in 6 full tests, AZ-900 (2026)
Every option explained — including the wrong ones
Readiness per exam domain, and drills for your weakest

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Frequently asked questions

VM vs App Service vs Functions — what's the one-line difference?

Azure Virtual Machines gives you a full OS to control (IaaS); Azure App Service hosts your web app without you managing servers (PaaS); Azure Functions runs event-driven code and bills per execution (serverless). Control drops and convenience rises as you move down that list.

When should I choose containers over the other options?

Reach for containers when you want portable, consistent deployments. Use Azure Container Instances for a single or short-lived container with no cluster to manage, and Azure Kubernetes Service when you need to orchestrate many containers at scale with automatic scaling and self-healing.

Are these real AZ-900 exam questions?

No. They are our own questions, written in the style and difficulty of the AZ-900 exam. Reproducing real exam items violates Microsoft's certification agreement and can cost you your certification, and a memorised item teaches you nothing about the one you have not seen.

Updated for AZ-900 (July 2026). The sample questions above are our own work in the style of the exam — not real exam items. The exam itself is set and marked by the certification body.