AZ-305 - Design Infrastructure Solutions - Section 4.1

Design compute solutions including virtual machines, containers, and serverless options.

Choose among virtual machine sizing and families, Azure Kubernetes Service, Azure Container Apps, Azure Functions, and App Service based on workload characteristics such as state, scale behaviour, and operational overhead. Weigh the trade-offs between infrastructure control and managed abstractions for a given performance and cost requirement.

VM sizing and familiesAzure Kubernetes ServiceAzure Container AppsAzure FunctionsApp Service

Practice question for this objective

Free sampleDesign Infrastructure Solutionsmedium

A regulated insurer must rehost a Windows-based intranet application that depends on COM components, MSI installers, registry adapters, and SMB drive mappings. The team wants the lowest-overhead Azure web-hosting model that supports those dependencies natively, without spinning up VMs or moving to containers. Which App Service hosting model does the quick decision guide recommend?

  • AStandard App Service plan on Windows
  • BManaged Instance on App Service (preview) Correct
  • CApp Service Environment with isolated VMs
  • DAzure Virtual Machines with IIS configured manually
Legacy Windows web apps with COM, MSI, registry, or drive-mapping dependencies map to the Managed Instance on App Service preview in the App Service quick decision guide. The App Service overview describes Managed Instance on App Service as the preview tier specifically built for legacy or infrastructure-bound Windows web apps that need Component Object Model, registry access, Microsoft Installers, drive mapping, or stricter network boundaries. The quick decision guide explicitly routes COM/registry/MSI/drive-mapping workloads to this option. The standard plan does not expose those Windows-host customisations, ASE solves a different problem (large-scale isolation), and VMs over-grant control and operational overhead.

Why A is wrong: A standard plan provides broad runtime flexibility and platform-managed OS patching but does not expose COM, MSI, registry, or drive-mapping customisation needed by the workload.

Why B is correct: Correct. The App Service overview describes Managed Instance on App Service as the preview tier specifically built for legacy or infrastructure-bound Windows web apps that need Component Object Model, registry access, Microsoft Installers, drive mapping, or stricter network boundaries.

Why C is wrong: ASE is the choice when the requirement is large-scale isolation across many apps, not deep per-plan OS customisation for COM/MSI/registry dependencies.

Why D is wrong: Virtual Machines work but force the team to manage OS, patching, and IIS themselves, which violates the lowest-overhead criterion.

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