Describe Azure architecture and services
Azure Compute and Application Hosting
CoreCompare virtual machines, containers, functions, VM options, and managed web hosting.
Aligned to the AZ-900 skills measured as of July 20, 2026; product behavior verified August 23, 2026.
Why this matters
Compute choices are differentiated by operating-system control, packaging, execution pattern, scaling purpose, and whether the outcome is a hosted application or a remote desktop.
Must Know
- A virtual machine provides a complete virtualized computer and guest OS under customer management.
- A container packages an application and dependencies while sharing the host operating-system kernel, making it lighter than a VM.
- A function runs code in response to events using a serverless execution model.
- Azure Virtual Machine Scale Sets manage groups of similar scalable VMs; availability sets spread VMs across fault and update domains; Azure Virtual Desktop delivers hosted desktop and application experiences.
- A VM needs compute sizing, an operating-system image, disks, and network connectivity. App Service offers managed web application hosting, while containers and VMs retain different levels of control.
Compare and Distinguish
- VM vs container vs function: full guest machine, packaged process, and event-driven serverless code.
- Scale Sets vs availability sets: scalable groups of VMs versus logical fault/update-domain distribution for VMs.
- Availability set vs availability zone: logical separation in datacenter infrastructure versus physically separate zone locations within a region.
- Web app vs container vs VM hosting: managed web platform, packaged runtime, and guest-OS control.
Scenario examples
- A legacy application requiring guest-OS control uses a VM.
- A portable packaged process uses a container.
- An event handler that runs briefly uses a function.
- A web application whose team wants managed platform hosting uses Azure App Service.
Exam traps
- A VM is more than CPU; disks, networking, and an OS image are also part of the conceptual resource set.
- Scale Sets and availability sets solve different problems.
- Application language alone does not select the hosting model.
Key takeaways
- Choose compute from isolation, control, and execution pattern.
- Keep scale, fault distribution, and remote desktop purposes separate.
- Managed web hosting reduces platform management; VMs maximize guest control.
Ready for the quiz?
- Which compute type best matches event-driven work?
- How does a Scale Set differ from an availability set?
- What resources does a VM conceptually require?
Related objectives
- D2.2.S1 — Compare compute types, including containers, virtual machines, and functions
- D2.2.S2 — Describe virtual machine options, including Azure virtual machines, Azure Virtual Machine Scale Sets, availability sets, and Azure Virtual Desktop
- D2.2.S3 — Describe the resources required for virtual machines
- D2.2.S4 — Describe application hosting options, including web apps, containers, and virtual machines