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Azure App Service: managed web apps for AZ-900

The PaaS way to host web apps and APIs without touching the OS — plus the four things the exam actually tests on it: plans, slots, scaling, and custom domains. AZ-900, 2026 edition.

Here are 7 typical App Service questions in the exam's own style — free, each answer explained, no sign-up.

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Azure App Service is the exam’s headline example of Platform as a Service (PaaS) for compute. You bring a web app or an API; Microsoft runs and patches the operating system and the language runtime underneath. That single idea — you deploy the code, Microsoft manages the platform — is the anchor for every App Service question, and the diagram above maps the four pieces the AZ-900 builds on top of it.

App Service is PaaS — and what that buys you

Because App Service is PaaS, you are not provisioning or maintaining servers. There is no OS to patch, no runtime to install by hand. You pick a stack — .NET, Java, Node.js, Python, PHP and more, on Windows or Linux — push your code, and it is live. That is the trade the exam wants you to recognise: less control than a virtual machine, far less to manage. If you need full control of the OS, you would reach for a VM (IaaS) instead.

The App Service Plan: the compute you pay for

Every app runs inside an App Service Plan. The plan is the compute tier: its region, its pricing tier (SKU), and the size and number of instances. It is the thing on your bill, and several apps can share one plan.

Tiers split two ways worth knowing cold:

  • Free / Shared — apps run on infrastructure shared with other customers. Fine for dev and test, limited in features.
  • Dedicated (Standard / Premium) — apps run on VMs reserved for you, and unlock the production features below: custom domains, autoscale, and deployment slots.

Deployment slots: swap staging into production

A deployment slot is a live copy of your app — commonly a “staging” slot — that shares the plan. You deploy the new version to staging, warm it up and test it, then swap: staging instantly becomes production with zero downtime. If something is wrong, you swap back just as fast. It is the safe-release feature, and it lives on the dedicated tiers.

Scale up vs scale out

Two words the exam deliberately contrasts:

  • Scale up (vertical) — move the plan to a bigger, more powerful tier: more CPU and memory per instance.
  • Scale out (horizontal) — run more instances of the app in parallel to share load. Autoscale does this automatically, adding and removing instances based on a metric like CPU or on a schedule.

Up = a bigger box; out = more boxes. Read the question for “bigger” versus “more,” as the axes in the diagram show.

Custom domains and TLS

By default an app answers at a azurewebsites.net address. On a supported tier you can add a custom domain so it responds at your own name, and bind a TLS/SSL certificate to serve it securely over HTTPS. “My own domain + HTTPS” is the giveaway for this pair.

The real exam mixes multiple-choice, true/false, and drag-and-drop formats; the seven questions below are standard multiple-choice, and every explanation carries a “why not the others” so the wrong options teach you as much as the right one.

A diagram of Microsoft Azure App Service. A large box labelled App Service Plan represents the compute tier you pay for and contains two hosted apps side by side: a Web App and an API. Below the plan, two labelled boxes show a Production slot and a Staging slot with a Swap arrow between them, illustrating a zero-downtime deployment swap. To the right, two axes describe scaling: a vertical Scale up axis meaning a bigger plan with more CPU and memory, and a horizontal Scale out axis meaning more instances running in parallel, driven by autoscale. A caption reads: App Service is PaaS — you deploy the code, Microsoft manages the operating system and runtime.

7 free AZ-900 practice questions

Answers and explanations — no email wall
AZ-900 Question 1 of 7

A team has a Node.js web app and a REST API they want online quickly. They are happy to hand off patching the operating system and updating the language runtime, but they still want to control their own application code and its configuration. Which Microsoft Azure service matches that division of responsibility?

Answer: A — Azure App Service — a Platform as a Service (PaaS) offering where Microsoft manages the OS and runtime and you own the code.

App Service is a PaaS compute service: Microsoft runs and patches the operating system and the language runtime, while you supply and configure the application. That is exactly the split described. Why not the others: a virtual machine is IaaS — the team would own OS patching and runtime installs, the opposite of what they asked for. Blob Storage holds files and can serve static assets but does not run a Node.js app or an API. Azure Policy governs which configurations are allowed; it hosts nothing. Pro tip: 'we want to deploy code but not manage the OS' is the App Service = PaaS signal.

AZ-900 Question 2 of 7

In App Service, what does the App Service Plan actually represent?

Answer: A — The compute resources — region, tier (pricing/SKU), instance size and count — that your apps run on and that you are billed for.

An App Service Plan defines the underlying compute your apps use: the region, the pricing tier (SKU), and the size and number of instances — and it is the thing you pay for. Multiple apps can share one plan and its resources. Why not the others: a support plan and its SLAs are a separate Azure offering, unrelated to hosting compute. A one- or three-year commitment describes a reservation, a cost tool, not the plan itself. DNS and custom-domain settings live on the app, not in the plan's definition. Pro tip: think of the App Service Plan as the 'server farm' your apps sit on — it is where cost and capacity are set.

AZ-900 Question 3 of 7

A company wants to isolate one production app on its own dedicated virtual machines with more memory and features like custom domains and autoscale, rather than sharing infrastructure with other tenants' apps. Which App Service Plan tier direction fits?

Answer: A — A dedicated (Standard/Premium) tier, which runs your apps on VMs reserved for you.

App Service offers Free and Shared tiers (good for dev/test, but running on infrastructure shared across customers and limited in features) and dedicated tiers such as Standard and Premium, which reserve VMs for your apps and unlock features like custom domains, autoscale, and staging slots. The requirement for isolation and richer features points to a dedicated tier. Why not the others: Free/Shared is the opposite of isolated. It is false that no dedicated option exists. A Consumption plan is the serverless model used by Azure Functions, not the standard App Service web-app hosting described. Pro tip: Free/Shared = shared hardware for testing; dedicated (Standard/Premium) = your own VMs plus the production features.

AZ-900 Question 4 of 7

Your team wants to deploy a new version to a non-production copy of the app, warm it up and test it, then put it live by exchanging it with production — instantly and with no downtime, and with the ability to roll back just as fast. Which App Service feature delivers this?

Answer: A — Deployment slots, using a slot swap.

Deployment slots are live app instances (for example a 'staging' slot) that share the plan. You deploy to staging, validate it, then swap slots — staging becomes production instantly with no downtime, and if something is wrong you swap back to roll it out. Why not the others: scaling out adds instances for load; it does not stage or swap a new version. Deleting and redeploying causes downtime and no safe rollback — the exact opposite of the goal. Advisor gives recommendations, not a deployment mechanism. Pro tip: 'test in staging, then swap to production with zero downtime' = deployment slots (a dedicated-tier feature).

AZ-900 Question 5 of 7

An App Service app is hitting CPU limits because more users are arriving. The team wants Azure to automatically add more identical instances of the app during busy periods and remove them when traffic drops. Is that scaling up or scaling out, and what enables it?

Answer: A — Scaling out — adding more instances — handled automatically by autoscale.

Scaling out (horizontal) means running more instances of the app in parallel; App Service can do this automatically with autoscale rules that add and remove instances based on a metric such as CPU or a schedule. Adding instances to spread load is scaling out. Why not the others: scaling up (vertical) means moving to a bigger tier with more CPU and memory per instance — useful, but that is not 'more instances.' The third option mislabels a bigger VM as scaling out. Instance count is not fixed — adjusting it is the whole point of scaling. Pro tip: up = bigger box (vertical), out = more boxes (horizontal); autoscale automates 'out'.

AZ-900 Question 6 of 7

During AZ-900 study you are asked which kinds of applications App Service can host. Which statement is accurate?

Answer: A — It runs web apps and APIs built in several languages and stacks — such as .NET, Java, Node.js, Python, PHP — on Windows or Linux.

App Service is a managed host for web apps, REST APIs, and mobile back ends across multiple languages and frameworks — .NET, Java, Node.js, Python, PHP and more — on both Windows and Linux. Why not the others: it is not limited to .NET or to Windows. It does far more than static HTML — that narrower need is what Azure Static Web Apps or Blob static hosting cover. It hosts web workloads, not arbitrary installed desktop .exe programs. Pro tip: App Service = managed hosting for web apps and APIs in mainstream languages; it is not tied to a single stack or OS.

AZ-900 Question 7 of 7

A public web app on App Service must be reachable at www.contoso.com and serve traffic over HTTPS with a valid certificate. Which two capabilities of App Service (on a supported tier) make this possible?

Answer: A — Custom domains, to map your own domain name, and TLS/SSL bindings, to serve the app over HTTPS.

App Service lets you add a custom domain so the app answers at your own name instead of the default azurewebsites.net address, and it supports TLS/SSL certificate bindings so that domain is served securely over HTTPS. Together they meet the requirement. Why not the others: deployment slots and autoscale handle releases and load, not naming or encryption. Azure Policy and resource locks are governance controls. A Log Analytics workspace with KQL is for querying logs. Pro tip: 'my own domain name + HTTPS' on App Service = custom domain binding + a TLS/SSL certificate, available on the dedicated tiers.

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 7 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
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  • Every option explained — including the wrong ones
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Frequently asked questions

When should I use App Service instead of just running a VM for my website?
Use App Service (PaaS) when you want to ship a web app or API and let Microsoft handle the operating system, patching, and runtime — you deploy the code and get built-in features like deployment slots, autoscale, custom domains, and TLS. Choose a virtual machine (IaaS) only when you need full control of the OS, custom software, or configurations App Service cannot provide. For most standard web apps, App Service is faster to run and less to maintain.
What is the difference between scaling up and scaling out in App Service?
Scaling up (vertical) means moving your App Service Plan to a bigger, more powerful tier — more CPU and memory per instance. Scaling out (horizontal) means running more instances of the app in parallel to share the load, which autoscale can do automatically based on demand or a schedule. Up = a bigger box; out = more boxes. The exam expects you to tell these two apart.
Are these real exam questions?
No. They are our own questions, written in the style and difficulty of the AZ-900 — never copied from any question bank or the real exam. Reproducing live exam items violates Microsoft's certification agreement and can cost a candidate their certification, and a crammed answer 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.