AZ-900 Cheat Sheet

Key concepts

• ✓Define and compare IaaS, PaaS, and SaaS with examples
• ✓Describe public, private, and hybrid cloud deployment models
• ✓Explain the shared responsibility model and who secures what
• ✓Differentiate between CapEx and OpEx and how cloud shifts costs
• ✓Identify benefits of cloud computing like scalability, elasticity, and high availability
• ✓Understand consumption-based pricing and its advantages

Watch out for

• ⚠Confusing IaaS with PaaS: IaaS gives you control over the OS and apps; PaaS only over apps
• ⚠Thinking public cloud is always cheaper than on-premises (it depends on workload)
• ⚠Mixing up scalability (adding resources) with elasticity (automatic scaling)
• ⚠Assuming the cloud provider is responsible for all security (shared responsibility model)

Key concepts

• ✓Identify the appropriate Azure compute service (e.g., VMs, App Service, Functions) for a given workload scenario
• ✓Differentiate between Azure storage options (Blob, Disk, File, Queue, Table) based on use case
• ✓Understand Azure networking concepts (VNet, load balancer, VPN Gateway, CDN) and their purposes
• ✓Describe Azure database services (SQL Database, Cosmos DB, Azure Database for MySQL/PostgreSQL) and when to use each
• ✓Explain Azure identity services (Azure AD, RBAC, MFA) and their role in security
• ✓Recognize Azure management tools (Portal, CLI, PowerShell, Cloud Shell) and their typical uses

Watch out for

• ⚠Confusing Azure Blob Storage (unstructured data) with Azure Files (managed file shares) or Azure Disk (VM disks)
• ⚠Thinking that availability zones and region pairs are the same thing—zones protect within a region, pairs protect across regions
• ⚠Assuming all virtual machines are IaaS, but Azure VMs are IaaS while App Service is PaaS—know the difference for scenario questions
• ⚠Mixing up Azure SQL Database (PaaS) with SQL Server on Azure VM (IaaS) in terms of management responsibility
• ⚠Forgetting that Azure AD is for identity and access management, not just Active Directory in the cloud—it's a separate service

Key concepts

• ✓Azure Policy – creating and assigning policies to enforce compliance rules
• ✓Role-Based Access Control (RBAC) – assigning roles like Owner, Contributor, Reader to users/groups
• ✓Resource locks – preventing accidental deletion or modification of resources
• ✓Tags – organizing resources with metadata for cost tracking and management
• ✓Azure Cost Management – setting budgets, analyzing costs, and using pricing calculator
• ✓Azure Blueprints – packaging policies, RBAC, and resource groups for repeatable deployments

Watch out for

• ⚠Confusing Azure Policy with Azure RBAC: Policy enforces rules on resources (e.g., 'must have a tag'), while RBAC controls who can access resources
• ⚠Thinking resource locks prevent all changes: Read-only lock prevents modification but not deletion; Delete lock prevents deletion but allows modification
• ⚠Assuming tags are inherited by default: Tags are not automatically inherited from resource groups to resources; you must apply them explicitly or use Azure Policy to enforce inheritance