Section 1: Architecture Fundamentals
1. What are the responsibilities of a .NET Architect?
Answer
A .NET Architect is responsible for:
Defining application architecture
Selecting appropriate technologies
Designing scalable systems
Reviewing code
Mentoring developers
Setting coding standards
Creating reusable frameworks
Cloud architecture
Performance optimization
Security governance
CI/CD implementation
Cost optimization
Risk management
Unlike a Tech Lead, an Architect focuses on long-term technical vision.
2. How do you design a scalable enterprise application?
Answer
I usually follow these principles:
Clean Architecture
SOLID Principles
Domain Driven Design (DDD)
CQRS where needed
Event-driven architecture
Microservices (if justified)
API-first development
Cloud-native deployment
Stateless services
Horizontal scaling
Typical layers:
Presentation
↓
Application
↓
Domain
↓
Infrastructure
↓
Database
3. What is Clean Architecture?
Answer
Clean Architecture separates business logic from external dependencies.
Layers
UI
↓
Application
↓
Domain
↓
Infrastructure
Benefits
Easy testing
Maintainability
Technology independence
Replace database without affecting business logic
Replace UI easily
4. What is Domain Driven Design (DDD)?
Answer
DDD focuses on modeling software around business domains.
Core concepts
Entity
Value Object
Aggregate
Repository
Domain Service
Bounded Context
Ubiquitous Language
DDD works well for
Banking
Insurance
ERP
Healthcare
Retail
5. Difference between Monolith and Microservices
| Monolith | Microservices |
|---|---|
| Single deployment | Multiple deployments |
| Easier initially | Complex initially |
| Hard to scale | Independent scaling |
| Tight coupling | Loose coupling |
| Shared database | Independent databases |
| Slower releases | Faster releases |
Section 2: ASP.NET Core
6. What are Middleware components?
Answer
Middleware handles HTTP requests.
Examples
Authentication
Authorization
Logging
Exception Handling
Routing
CORS
Response Compression
Pipeline
Request
↓
Authentication
↓
Authorization
↓
Controller
↓
Response
7. Explain Dependency Injection.
Answer
ASP.NET Core has built-in DI.
Lifetimes
Transient
New object every request
Scoped
One object per HTTP request
Singleton
One object for application lifetime
8. What is Minimal API?
Answer
Minimal APIs reduce boilerplate.
Example
app.MapGet("/users", () =>
{
return users;
});
Advantages
Lightweight
Faster startup
Great for microservices
Section 3: Microservices
9. When should Microservices NOT be used?
Answer
Avoid when
Small application
Small team
Low traffic
Tight deadlines
Shared transactions
Limited DevOps maturity
10. Communication between Microservices?
Answer
Synchronous
REST
gRPC
Asynchronous
RabbitMQ
Azure Service Bus
Kafka
11. How do you manage distributed transactions?
Answer
Avoid two-phase commit.
Use
Saga Pattern
Eventual Consistency
Outbox Pattern
12. API Gateway advantages?
Answer
Provides
Authentication
Rate limiting
Routing
Caching
Load balancing
Logging
Versioning
Examples
Azure API Management
Kong
Ocelot
YARP
Section 4: Azure Cloud
13. Which Azure services do you commonly use?
Answer
Azure App Service
Azure Functions
Azure Kubernetes Service
Azure SQL
Cosmos DB
Azure Key Vault
Azure Service Bus
Azure Storage
Azure Monitor
Azure Application Insights
Azure Front Door
14. Difference between Azure Functions and App Service?
| Azure Functions | App Service |
|---|---|
| Event driven | Web apps |
| Pay per execution | Always running |
| Serverless | Dedicated hosting |
| Background jobs | APIs |
15. What is Azure Key Vault?
Answer
Stores
Secrets
Passwords
Certificates
Connection Strings
Encryption Keys
Never hardcode secrets.
Section 5: Security
16. Authentication vs Authorization
Authentication
Who are you?
Authorization
What can you access?
17. JWT Authentication?
Answer
JWT contains
Header
Payload
Signature
Advantages
Stateless
Fast
Secure
Scalable
18. OWASP Top Risks?
Answer
SQL Injection
XSS
CSRF
Broken Authentication
Broken Access Control
Security Misconfiguration
19. How do you secure APIs?
Answer
OAuth2
JWT
HTTPS
API Gateway
Rate limiting
Input validation
Logging
Secrets in Key Vault
Section 6: Performance
20. Performance optimization techniques?
Answer
Redis caching
Async programming
Connection pooling
Pagination
Compression
Lazy loading
CDN
Database indexing
21. How do you identify bottlenecks?
Tools
Application Insights
dotTrace
PerfView
SQL Profiler
BenchmarkDotNet
Section 7: Entity Framework
22. How do you optimize EF Core?
Answer
Use
AsNoTracking()
Avoid
N+1 Queries
Use
Projection
Compiled Queries
Indexes
Batch updates
Section 8: Distributed Systems
23. CAP Theorem?
Answer
Choose only two
Consistency
Availability
Partition Tolerance
Cloud systems usually choose
Availability + Partition Tolerance
24. Eventual Consistency?
Answer
All systems eventually become consistent.
Examples
Amazon
Netflix
Banking
Section 9: DevOps
25. CI/CD Pipeline?
Stages
Build
↓
Unit Tests
↓
Static Analysis
↓
Docker Build
↓
Deploy Dev
↓
Integration Tests
↓
Deploy QA
↓
Approval
↓
Production
26. Infrastructure as Code?
Tools
Terraform
Bicep
ARM Templates
Pulumi
27. Blue Green Deployment?
Answer
Two environments
Blue
Green
Switch traffic after validation.
28. Canary Deployment?
Answer
Deploy to
5%
↓
20%
↓
50%
↓
100%
Section 10: Kubernetes
29. Why Kubernetes?
Answer
Auto scaling
Self healing
Rolling updates
Service discovery
High availability
30. Difference between Pod and Deployment?
Pod
Single running container
Deployment
Manages Pods
Section 11: Design Patterns
31. Most used patterns?
Repository
Factory
Mediator
Strategy
Observer
Builder
Decorator
CQRS
Unit of Work
32. SOLID Principles?
S
Single Responsibility
O
Open Closed
L
Liskov
I
Interface Segregation
D
Dependency Inversion
Section 12: Leadership
33. How do you mentor developers?
Answer
Architecture sessions
Pair programming
Code reviews
Documentation
Technical workshops
Design discussions
34. How do you conduct code reviews?
Check
Security
Performance
Naming
Readability
Design
Test coverage
35. How do you handle technical debt?
Answer
Prioritize
Measure impact
Refactor incrementally
Add automation
Document debt
Section 13: AI Assisted Development
36. How do you use AI in development?
Answer
AI tools like ChatGPT, GitHub Copilot, and Microsoft Copilot can help with:
Generating boilerplate code
Writing unit tests
Refactoring code
Creating documentation
Explaining legacy code
Generating SQL queries
Reviewing code for best practices
Creating CI/CD pipeline templates
Generating API documentation
However, AI-generated code must always undergo human review for correctness, security, maintainability, and compliance with organizational standards.
37. Risks of AI-generated code?
Answer
Security vulnerabilities
Hallucinated APIs
Incorrect business logic
Licensing concerns
Outdated practices
Over-reliance reducing developer understanding
Mitigation includes code reviews, automated security scans, static analysis, and comprehensive testing.
Section 14: Scenario-Based Questions
38. A microservice is slow. How would you troubleshoot it?
Answer:
Review application logs and distributed traces.
Monitor CPU, memory, and network usage.
Identify slow database queries.
Check external API dependencies.
Analyze thread pool starvation or blocking calls.
Verify cache hit/miss ratios.
Profile the application using performance tools.
Implement optimizations and validate improvements.
39. Your application must support 10 million users. How would you design it?
Answer:
Stateless microservices
Load balancers
Azure Kubernetes Service (AKS)
Azure Front Door/CDN
Redis distributed cache
Cosmos DB or SQL with read replicas
Event-driven messaging (Service Bus/Kafka)
Auto-scaling
Monitoring with Application Insights
Disaster recovery across regions
40. How do you ensure high availability?
Answer:
Multi-region deployment
Load balancing
Health probes
Auto-healing containers
Database failover
Backup and restore strategy
Circuit Breaker and Retry patterns
Chaos testing
Section 15: Common Architecture Interview Questions
Explain CQRS.
Explain Event Sourcing.
Explain Saga Pattern.
Explain Circuit Breaker.
Explain Bulkhead Pattern.
Explain Retry Pattern.
Explain Idempotency.
Explain API Versioning.
Explain Distributed Caching.
Explain Zero Trust Security.
Explain OAuth2.
Explain OpenID Connect.
Explain gRPC.
Explain GraphQL.
Explain Message Queues.
Explain Event Bus.
Explain Azure Service Bus vs RabbitMQ vs Kafka.
Explain Redis.
Explain Horizontal Scaling vs Vertical Scaling.
Explain Observability (Logs, Metrics, Traces).
Tips for a .NET Architect Interview
Interviewers often look for more than technical knowledge. Be prepared to:
Explain the reasoning behind architectural decisions and discuss trade-offs rather than presenting one solution as universally correct.
Draw architecture diagrams for layered applications, microservices, event-driven systems, and cloud deployments.
Demonstrate knowledge of Azure services, Kubernetes, Docker, CI/CD pipelines, and Infrastructure as Code.
Discuss how you enforce coding standards, security, and governance across engineering teams.
Explain how you balance scalability, performance, maintainability, cost, and delivery timelines.
Share real-world examples of leading technical initiatives, mentoring developers, and collaborating with stakeholders.
Describe responsible use of AI-assisted development tools, emphasizing human review, testing, and secure coding practices.
These questions represent the level of discussion commonly expected for a Senior .NET Architect role with enterprise application, cloud-native, DevOps, security, and AI-assisted development responsibilities.
