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 it's wrong here

  With Azure Virtual Machines, you have full control and responsibility for the OS, middleware, and application, and you must configure virtual machine scale sets or load balancers yourself to achieve auto-scaling. This adds significant operational overhead for patching, backups, and high availability, which is unnecessary for a simple web app that App Service provides out of the box. Additionally, scaling a VM-based solution typically requires more time and planning than the platform-managed scaling in App Service.

• ✓

  Azure App Service

  Why this is correct

  Azure App Service is a fully managed Platform-as-a-Service (PaaS) offering specifically designed for hosting web applications, REST APIs, and mobile backends. It includes built-in auto-scaling capabilities based on metrics or schedules, as well as automatic patching, load balancing, and high availability, without requiring you to manage infrastructure. This makes it the optimal choice for a web app that needs to handle variable traffic with minimal operational effort.

• ✗

  Azure Batch

  Why it's wrong here

  Azure Batch is a job scheduling service for running large-scale parallel and high-performance computing applications, such as rendering, simulations, or financial risk modeling. It orchestrates pools of compute nodes and schedules tasks, but it does not provide the continuous runtime or built-in HTTP endpoints needed to host a web application. Therefore, it is fundamentally misaligned with the requirement of auto-scaling a web app for end-user traffic.

• ✗

  Azure Container Instances

  Why it's wrong here

  Azure Container Instances is a serverless container service that launches containers on demand, but it lacks built-in auto-scaling rules, load balancing, and rolling update capabilities that web apps require. It's designed for isolated tasks or burst workloads, not as a managed web hosting platform with continuous scaling. Even though you can run a web server in a container, you'd have to build your own scaling and availability logic, making it less suitable than a PaaS web app service.