AZ-900 Exam Notes

Azure Regions and Availability Zones

Azure provides over 60 regions globally. Here’s what you need to know:

• Regions are geographical locations.
• Deploy services to multiple regions for high availability, low latency, and geographical reach.
• Azure offers multiple availability zones in a single region.
• Each zone has its own power resources and network connectivity.
• Zones are connected with low-latency links for high availability within the same region.
• Not all Azure regions have availability zones.
• Examples of regions and their availability zones:
• East US - 3
• West Europe - 3
• Southeast Asia - 3
• West Central US - 0

Subscription, Resource Groups, Management Groups, and Tags

• Resource Groups contain resources like Virtual Machines, databases, etc.
• Each resource group is associated with one Azure subscription.
• Azure resource hierarchy: Management Groups → Subscription → Resource Group → Resources.
• Resources can only belong to one resource group, but resource groups can span multiple regions.
• Resource groups are free; you only pay for the resources.
• Permissions applied to a resource group are inherited by its resources.
• Tags help categorize resources for tracking and reporting. They do not automatically inherit from the resource group.

Virtual Machines, Availability Set, and Scale Set

• Deploy applications in the cloud on a Virtual Machine (VM).
• SLAs vary based on disk type:
• Premium SSD/Ultra Disk - 99.9%
• Standard SSD - 99.5%
• Standard HDD - 95%
• Availability Sets group VMs logically to improve availability.
• Fault Domain: Shared network and power for VMs.
• Update Domain: VMs restarted together during maintenance.
• VM Scale Sets allow auto/manual scaling up to 1000 instances.
• Auto-scaling is based on CPU, memory, etc.

IaaS, PaaS, SaaS, and Containers

• IaaS: You manage infrastructure. Example: Virtual Machines, databases, OS.
• PaaS: Only responsible for application deployment. Example: Azure App Service, Cosmos DB.
• SaaS: Responsible only for using applications. Example: Office 365, Dropbox.
• Azure Containers virtualize software; no need for VM management.
• Azure Service Fabric and Kubernetes offer container orchestration.

Public, Private, and Hybrid Clouds

• Public Cloud: Hosted by Azure, no CapEx, pay-as-you-go model.
• Private Cloud: On-premise, high CapEx, high security and privacy.
• Hybrid Cloud: Combination of public and private clouds.

Serverless, Azure Functions, and Logic Apps

• Serverless means zero visibility of servers. Example: Azure Functions.
• Azure Functions are auto-scalable and pay-as-you-go.
• Logic Apps offer serverless orchestration with GUI-based design.

Azure Storage

• Azure provides file storage (Azure Files), block storage (Azure Disks), and object storage (Blob Storage).
• Different redundancy options available:
• LRS: 3 copies in one data center.
• ZRS: 3 copies across zones in a region.
• GRS: LRS + async copy to secondary region.
• GZRS: ZRS + async copy to secondary region.

Azure Databases

• Azure SQL Database: Managed SQL service with 99.99% availability.
• Azure Cosmos DB: Low-latency NoSQL database.
• Azure Cache for Redis: In-memory data store for fast applications.

Azure Networking

• Azure Virtual Network (VNet) acts like an isolated network in the Azure cloud.
• Subnets help separate public/private resources within VNets.
• NSGs (Network Security Groups) control traffic between resources.
• Azure Firewall is a managed, centralized firewall service.

Azure Security

• Azure Security Center offers security monitoring and recommendations.
• Azure Key Vault stores secrets like API keys and certificates securely.
• Azure AD helps manage identity and access control with MFA and Conditional Access.

Azure Management Tools

• Azure Advisor: Provides recommendations for security and cost optimization.
• Azure Monitor: Analyzes logs and metrics across resources.
• Azure Service Health: Dashboard for service outages, updates, and decommissioned services.

Azure Service Level Agreement (SLA)

• Azure gives service credits if SLA is not met.
• Phases of Azure Service Lifecycle: Private Preview, Public Preview, General Availability.

Azure Compliance, Privacy, and Governance

• Azure Policies help ensure resources comply with standards.
• Azure Blueprints combine policies, roles, and resource groups for governance.
• GDPR compliance ensures personal data protection for users in Europe.