Application hosting: Web Apps, containers, and virtual machines¶
Once you know what runs (web app, API, container, custom server), choose where to host it based on control, management effort, and scenario keywords.
Compare hosting options¶
| Requirement | Likely answer |
|---|---|
| Host a web app or API without managing the OS | Azure App Service (Web Apps) |
| Run containers with orchestration | Azure Kubernetes Service |
| Run a simple container without cluster management | Azure Container Instances |
| Full control of OS and installed software | Azure Virtual Machines |
| Event-driven code with no server admin | Azure Functions |
Azure App Service¶
App Service is a PaaS platform for hosting web apps, REST APIs, and mobile backends.
Choose App Service when the scenario mentions:
- deploy code or containers to a managed web platform;
- built-in scaling, deployment slots, and HTTPS;
- no OS patching by the development team;
- .NET, Java, Node.js, Python, PHP, or containerized web workloads on a managed platform.
App Service is the default AZ-900 answer for managed web application hosting.
Containers as application hosting¶
Containers can run on:
- App Service for web-focused container hosting;
- Container Instances for simpler, shorter-lived runs;
- AKS for larger microservice architectures.
Exam clue: "web app without managing servers" usually points to App Service, not AKS, unless the scenario emphasizes orchestration across many services.
Virtual Machines for applications¶
Use VMs when the application needs:
- a specific OS configuration;
- software that App Service does not support;
- maximum control comparable to an on-premises server.
The trade-off is more patching, scaling, and availability design work for the customer.
Scenario¶
A team has a Node.js REST API and wants HTTPS, deployment slots, and autoscale without managing virtual machines.
Best fit: Azure App Service.
Scenario¶
A company runs a custom ERP system that requires a specific Windows Server role and third-party drivers.
Best fit: Azure Virtual Machines.
Exam clues¶
- Managed web platform, no OS patching → App Service.
- Many identical web servers behind a load balancer with VM control → VMSS on VMs, not App Service.
- Microservices fleet with Kubernetes → AKS.
- Legacy server with custom OS setup → VM.