AZ-900 Course Notes

AZ-900 cloud concept questions usually test comparisons. If the question says resources can grow or shrink as demand changes, think elasticity. If it says adding more instances or capacity to handle more users, think scalability. If it says an app stays available during a datacenter problem, think high availability or fault tolerance instead of cost savings.

• Choosing scalability when the clue says resources automatically add and remove with demand; that wording points to elasticity.

• If the wording says pay only for what you use, think consumption-based pricing.

AZ-900 management questions often ask which tool matches the job. Use the Azure portal when the clue says web-based graphical interface. Use Azure CLI or Cloud Shell when the clue says command line or scripting. Use Bicep or infrastructure as code when the clue says repeatable deployments, templates, or describing resources in files.

• Using Azure Monitor for cost estimation even though Pricing Calculator estimates cost before deployment.

• Pricing Calculator estimates before deployment; Cost Management analyzes actual spend.

Azure architecture questions often ask which container or boundary is being described. A resource group holds related resources for one app or workload. A subscription is the billing and access boundary. A management group sits above subscriptions so governance can be applied to many subscriptions. If the question says organize multiple subscriptions, do not pick resource group.

• Confusing a region with an Availability Zone; a zone is inside a supported region.

• Regions are geographic areas; Availability Zones are separate datacenter locations inside supported regions.

Azure service questions are usually about recognizing what problem the service solves. Virtual Machines are the answer when the workload needs operating system control. App Service is the answer for managed web apps and APIs. Functions is the answer for short event-driven code. If the question says container orchestration or managing many containers, AKS is the likely service, but AZ-900 does not expect deep Kubernetes administration.

• Choosing Azure Functions for a full web app when App Service is the managed web app hosting clue.

• Blob Storage stores objects; Azure Files provides file shares.

Governance questions ask how Azure is organized and controlled. Subscriptions separate billing, access, and resource limits. Management groups organize multiple subscriptions. Resource groups organize related resources. Azure Policy enforces rules such as allowed regions or required tags. If the clue says organize many subscriptions, choose management groups; if it says enforce a rule, choose Policy.

• Choosing Azure Policy for cost alerts; budgets are used for spending threshold alerts.

• Management groups organize subscriptions above the subscription level.

Cloud model questions on AZ-900 reward simple keyword matching. Virtual Machines mean IaaS because the customer manages the OS. App Service, Azure SQL Database, and managed database platforms feel like PaaS because Microsoft manages more of the platform. Microsoft 365-style complete apps are SaaS. If the question asks who manages the application itself, SaaS is usually the answer.

• Choosing PaaS when the question says the customer manages the operating system; that points to IaaS.

• VM equals IaaS; App Service and Azure SQL Database often point to PaaS; Microsoft 365 style apps point to SaaS.