AZ-900 Describe Azure architecture and services Practice Question

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 Virtual Machines

  Why this is correct

  Azure Virtual Machines are an Infrastructure-as-a-Service offering where each VM has its own Linux guest OS running on a Microsoft-managed hypervisor. You have full root/administrator access, letting you install custom kernel modules, use specialized drivers, modify system configuration, and run any long-lived application. This provides the complete OS-level control the scenario requires.

• ✗

  Azure App Service

  Why it's wrong here

  Azure App Service is a fully managed Platform-as-a-Service; Azure handles the OS patching, scaling, and infrastructure, and you only deploy application code or a container. You have no direct access to the underlying VM or host, so you cannot install system-level packages, modify the kernel, or perform OS configuration. Even when using a custom Linux container, the host remains abstracted and outside your control.

  When this WOULD be correct

  A company wants to deploy a web application or API using a supported stack (e.g., .NET, Java, Node.js) without managing the underlying infrastructure. They need automatic scaling, built-in load balancing, and managed security patching, but do not require OS-level access.

• ✗

  Azure Container Instances

  Why it's wrong here

  Azure Container Instances runs container images on Azure-managed compute where all containers on a node share the host OS kernel. Although you can package your application and its user-space dependencies into the image, you cannot manage the OS kernel, load kernel modules, or change host-level system settings because the underlying virtual machines are wholly operated by the Azure platform. Isolation is provided via cgroups and namespaces, not a separate guest OS.

  When this WOULD be correct

  A company wants to deploy a containerized application quickly without managing underlying VMs, and they need fast startup and per-second billing. For example, a batch processing job that runs in a Docker container and requires no OS customization.

• ✗

  Azure Functions

  Why it's wrong here

  Azure Functions is a serverless Function-as-a-Service platform that triggers execution of small pieces of code for discrete events, with Azure managing the runtime and scaling automatically. You only supply code and configuration files, and the functions run in a managed, ephemeral sandbox with no capability to install OS software, access the host filesystem, or alter the execution environment. This model is opposite to full OS control and fits short-lived, event-driven workloads only.

  When this WOULD be correct

  A question that asks for a serverless compute service to run a small piece of code in response to an event (e.g., processing a blob upload) without managing infrastructure, where the code runs for a short duration and scales automatically.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”