My curated list
There are plenty of resources out there to help you study for the AZ-900 exam. The exam is for candidates who are just beginning to work with cloud-based solutions and services.
It’s an opportunity to gather knowledge of cloud concepts, services, workloads, security, privacy, pricing and support. Here comes my list:
Cloud Concepts
Benefits
https://docs.microsoft.com/en-us/learn/modules/fundamental-azure-concepts/benefits-of-cloud-computing
Elastic
https://azure.microsoft.com/en-us/overview/what-is-elastic-computing/
Consumption and fixed cost models
https://docs.microsoft.com/en-us/azure/architecture/framework/cost/design-price
Shared responsibility
https://docs.microsoft.com/en-us/azure/security/fundamentals/shared-responsibility
Cloud Computing
https://docs.microsoft.com/en-us/learn/modules/fundamental-azure-concepts/types-of-cloud-computing
IAAS
https://azure.microsoft.com/en-us/overview/what-is-iaas/
PAAS
https://azure.microsoft.com/en-us/overview/what-is-paas/
SAAS
https://azure.microsoft.com/en-us/overview/what-is-saas/
Cloud Models
https://azure.microsoft.com/en-us/overview/what-are-private-public-hybrid-clouds/
Public cloud
https://azure.microsoft.com/en-gb/overview/what-is-a-public-cloud/
Geographies
https://azure.microsoft.com/en-us/global-infrastructure/geographies/#overview
Region and availability zones
https://docs.microsoft.com/en-us/learn/modules/azure-architecture-fundamentals/regions-availability-zones
Compute
https://azure.microsoft.com/en-us/product-categories/compute/
Virtual machines
https://docs.microsoft.com/en-us/learn/modules/azure-compute-fundamentals/azure-virtual-machines
Serverless
https://docs.microsoft.com/en-us/learn/modules/azure-compute-fundamentals/azure-functions
Previews
https://azure.microsoft.com/en-us/support/legal/preview-supplemental-terms/
Pricing
https://docs.microsoft.com/en-us/learn/modules/plan-manage-azure-costs/ https://azure.microsoft.com/en-us/pricing/calculator/
https://azure.microsoft.com/en-us/pricing/tco/calculator/
Core Solutions
Big Data
https://docs.microsoft.com/en-us/azure/architecture/guide/architecture-styles/big-data
IoT
https://docs.microsoft.com/en-us/azure/iot-fundamentals/iot-introduction
Cognitive Services
https://azure.microsoft.com/en-us/services/cognitive-services/
Goverance
Strategy
https://docs.microsoft.com/en-us/learn/modules/build-cloud-governance-strategy-azure/
Resource Groups
https://docs.microsoft.com/en-us/azure/azure-resource-manager/management/overview#resource-groups
Azure Management Groups
https://docs.microsoft.com/en-us/azure/governance/management-groups/overview
Policy
https://docs.microsoft.com/en-us/azure/governance/policy/overview
Blueprints
https://docs.microsoft.com/en-us/learn/modules/build-cloud-governance-strategy-azure/8-govern-subscriptions-azure-blueprints
Identity & Access
Azure AD
https://docs.microsoft.com/en-us/azure/active-directory/fundamentals/active-directory-whatis
SSO
https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/what-is-single-sign-on
MFA
https://docs.microsoft.com/en-us/azure/active-directory/authentication/concept-mfa-howitworks
Management Tools
Azure Advisor
https://docs.microsoft.com/en-us/azure/advisor/
Azure Cloud Shell
https://docs.microsoft.com/en-us/azure/cloud-shell/overview
Azure Cost Management
https://docs.microsoft.com/en-us/learn/paths/az-900-describe-azure-cost-management-service-level-agreements/
Azure Key Vault
https://docs.microsoft.com/en-us/azure/key-vault/
Azure Monitor
https://docs.microsoft.com/en-us/azure/azure-monitor/overview
Azure Resource Manager
https://docs.microsoft.com/en-us/azure/azure-resource-manager/management/overview
Azure Service Health
https://docs.microsoft.com/en-us/azure/service-health/overview
Azure Service Trust
https://servicetrust.microsoft.com/
Network & Security
Network
https://docs.microsoft.com/en-us/azure/security/fundamentals/network-overview
CDN
https://docs.microsoft.com/en-us/azure/cdn/cdn-overview
Load Balancing
https://docs.microsoft.com/en-us/azure/architecture/guide/technology-choices/load-balancing-overview
Defense in depth
https://docs.microsoft.com/en-us/learn/modules/secure-network-connectivity-azure/2-what-is-defense-in-depth
Perimeter networks
https://docs.microsoft.com/en-us/azure/cloud-adoption-framework/ready/azure-best-practices/perimeter-networks
Network Security
https://docs.microsoft.com/en-us/azure/cloud-adoption-framework/ready/considerations/networking-options
Network Security Groups
https://docs.microsoft.com/en-us/azure/virtual-network/network-security-groups-overview
DDoS
https://docs.microsoft.com/en-us/azure/ddos-protection/ddos-protection-overview
I hope this list helps you.