Microsoft Azure Mastery for .NET Architects

Case Study: Global retail scaling with Cosmos DB and AKS

1 Views Updated 5/4/2026

Case Study: Black Friday at Scale

The Challenge: A global retailer needs to handle 100,000 orders per minute during Black Friday while maintaining a 1-second page load time for users in the US, Europe, and Asia.

1. The Architecture

We deployed the .NET 8 order service to **AKS clusters** in three regions (East US, West Europe, East Asia). We used **Azure Front Door** to route users to the nearest cluster. All clusters shared a single **Cosmos DB** database with **Multi-Region Writes** enabled.

2. The "Elastic" Result

During the peak hour, the AKS clusters auto-scaled from 20 to 800 pods per region. Cosmos DB RUs automatically scaled from 40k to 1 million. Because the data was physically close to the users (in their local region) and handled by a massively parallel compute fleet, the average API response time stayed under **45ms**.

3. Conclusion

By leveraging the 'Global Fabric' of Azure, we built a system that cost $200 a day normally, but could handle the world's largest shopping event with zero downtime and perfect performance. Architecture is the art of building for the peak while paying for the valley.

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Microsoft Azure Mastery for .NET Architects
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
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8. Enterprise Scale & Patterns
Cloud Adoption Framework (CAF): The Architect's strategy Case Study: Global retail scaling with Cosmos DB and AKS