Microservices Mastery

C# Architect Interview: Microservices & System Design Focus

1 Views Updated 5/4/2026

Architect Interview Final

Congratulations! You have completed the full 180+ module Toolliyo curriculum. In this final module, we focus on the high-level **System Design** questions asked at the Senior and Staff Engineer level for Microservices positions.

1. Scenario: Scale a global e-commerce site

Question: "How would you design a system to handle 100,000 orders per second during Black Friday?"

Answer Structure:

  • Frontend: Static assets on a CDN (Azure Front Door / Cloudflare).
  • Entry: API Gateway with Rate Limiting and Circuit Breakers.
  • Auth: Cached JWT tokens in Redis.
  • Write Path: Queue all orders in RabbitMQ/Service Bus immediately to decouple processing from the UI.
  • database: Sharded PostgreSQL or a NoSQL database like CosmosDB for unlimited write throughput.
  • Observability: Real-time dashboards with OpenTelemetry to spot hotspots instantly.

2. The CAP Theorem Decision

In a distributed system, you can only have two out of three: **Consistency**, **Availability**, and **Partition Tolerance**. For a modern microservice app, we almost always choose **AP** (Availability & Partition Tolerance). We accept that data might be slightly stale for a few milliseconds (Eventual Consistency) in exchange for the system NEVER going down.

MASTER ARCHITECT CAPSTONE COMPLETE.

You are now ready to lead enterprise-grade .NET teams and design cloud-native systems for millions of users. Keep building.

Microservices Mastery
1. Distributed Systems Fundamentals
Monolith vs Microservices: When to migrate? The 12-Factor App Methodology for Cloud-Native Apps Database Per Service: Handling distributed data consistency
2. Containerization & Orchestration
Docker Essentials: Building efficient .NET images Docker Compose: Orchestrating a multi-service environment Kubernetes Architecture: Pods, Services, and Deployments K8s ConfigMaps & Secrets: Managing environment variables Helm Charts: Packaging your microservices for K8s
3. Service Communication
Synchronous vs Asynchronous Communication: Pros and Cons REST APIs in a Microservices World: Best Practices Mastering gRPC: High-performance binary communication API Gateways: Implementing Ocelot for single-entry access BFF Pattern: Backend-for-Frontend (Mobile vs Web)
4. Event-Driven Architecture
Message Brokers: Introduction to RabbitMQ & Azure Service Bus Pub/Sub Pattern: Implementing MassTransit for .NET The Outbox Pattern: Ensuring 100% data consistency Dead Letter Queues: Handling message failure gracefully Distributed Transactions: The Saga Pattern (State Machines)
5. Resilience & Scalability
Distributed Caching with Redis: Optimizing global state Service Discovery: IdentityServer4 & Consul Load Balancing: Nginx vs Ingress Controllers The Sidecar Pattern: Offloading cross-cutting concerns
6. Observability & Security
Distributed Logging with Serilog & SEQ Distributed Tracing: OpenTelemetry & Jaeger Health Checks: Monitoring system vitals in real-time OAuth2 & OpenID Connect: Centralized Identity (AuthN/AuthZ) Rate Limiting & Throttling: Protecting your services
7. Advanced Cloud Topics
Infrastructure as Code (IaC): Introduction to Terraform CI/CD Pipelines for Microservices (GitHub Actions/Azure DevOps) C# Architect Interview: Microservices & System Design Focus