Microsoft Azure Mastery for .NET Architects
Lesson 2 of 30 7% of course

App Registrations & Service Principals: Secure machine identity

15 · 8 min · 5/23/2026

Sign in to track progress and bookmarks.

Machine Identities

In Azure, applications don't log in with passwords. They use App Registrations and Service Principals.

1. The Difference

App Registration: The 'Template' or 'Blueprint' of your application defined in your Entra ID tenant.
Service Principal: The 'Instance' of that application with specific permissions in a specific subscription. Think of it as a 'User Account' for a piece of code.

2. Managed Identities

The 'Architect's Holy Grail'. Managed Identities allow your Azure resources (like App Service or Lambda-equivalent Functions) to talk to other Azure resources (like SQL or Key Vault) WITHOUT you managing any Client IDs or Secrets. Azure handles the rotation automatically. **Rule:** Always use Managed Identity if the service supports it.

3. Architect Insight

Q: "Where are the secrets stored for App Registrations?"

Architect Answer: "You can use **Client Secrets** (passwords) or **Certificates**. For production, always use Certificates. Secrets expire and are often accidentally committed to Git. Certificates provide a much higher level of security and can be managed centrally in Azure Key Vault."

Test your knowledge

Quizzes linked to this course—pass to earn certificates.

Browse all quizzes
Microsoft Azure Mastery for .NET Architects

On this page

1. The Difference 2. Managed Identities 3. Architect Insight
1. Azure Identity & Governance
Microsoft Entra ID (Azure AD): Scaling identity for .NET apps App Registrations & Service Principals: Secure machine identity Azure Policy & Blueprints: Enforcing architecture standards Resource Groups & Management Groups: Organizing the Cloud
2. Azure Web & Compute
Azure App Service: Managed hosting for ASP.NET Core Azure Functions: Serverless logic with Durable Functions Azure Container Apps (ACA): Serverless K8s for microservices Azure Kubernetes Service (AKS): Enterprise orchestration
3. Azure Databases
Azure SQL Database: The king of cloud-native SQL Azure Cosmos DB: Global scale with multi-model NoSQL Azure Cache for Redis: Managed memory performance Azure Database for PostgreSQL/MySQL: Flexible server scaling
4. Networking & Security
Azure Virtual Network (VNet): Subnets, Peering, and Gateways Azure Front Door: Global CDN & Load Balancing Azure Key Vault: Managing secrets, keys, and certificates Azure Application Gateway (WAF): Protecting the front-end
5. Messaging & Integration
Azure Service Bus: Enterprise-grade message queuing Azure Event Grid: Building reactive, event-driven systems Azure Event Hubs: Large-scale data ingestion for .NET Logic Apps: No-code orchestration for .NET developers
6. AI & Data Services
Azure OpenAI Service: Integrating GPT into .NET apps Cognitive Services: Vision, Speech, and Language APIs Azure Search (AI Search): Semantic search and vector indexing Azure Data Factory: ETL and data movement
7. Monitoring & Hybrid
Azure Monitor & Application Insights: Deep .NET observability Log Analytics: KQL (Kusto) for large-scale log analysis Azure Arc: Managing on-premise and multi-cloud from Azure Azure Bicep: Modern Infrastructure as Code for Azure
8. Enterprise Scale & Patterns
Cloud Adoption Framework (CAF): The Architect's strategy Case Study: Global retail scaling with Cosmos DB and AKS