AZ-900 asks you to recognize the major Azure services by category:

• Compute: Virtual Machines (IaaS), App Service (PaaS web apps), Azure Functions (serverless), AKS (managed Kubernetes), Container Instances
• Storage: Blob (object), Files (SMB shares), Disks (VM storage), Queues
• Networking: Virtual Network (VNet), Load Balancer, VPN/ExpressRoute, Azure DNS
• Databases: Azure SQL Database, Cosmos DB (NoSQL, global), Database for PostgreSQL/MySQL

You don’t need deep configuration knowledge — just which service solves which problem and where it sits on the IaaS/PaaS spectrum.

Scenario → Service
  Run a lift-and-shift Windows app   → Virtual Machine (IaaS)
  Host a scalable web API, no servers → App Service (PaaS)
  Process an image when uploaded     → Azure Functions (serverless)
  Store user uploads cheaply         → Blob Storage
  Global, low-latency NoSQL          → Cosmos DB
  Connect resources privately        → Virtual Network

1. Match three workloads to the right compute service and justify each.
2. Name the Azure storage type for object data, file shares, and VM disks.
3. Explain when you’d choose App Service over a Virtual Machine.
4. Draw the resource hierarchy from management group down to a resource.

• ↗ Microsoft Learn — Azure core services