Technical Interview: Complete Guide to Oral Exams (DevOps, APIs, Microservices & More)

Oral Interview Questions & Answers

(Oral Exam Preparation)

1. DevOps & CI/CD

Q: Explain the impact of CI/CD in your work.
A:
"CI/CD automates testing and deployment, reducing human errors and accelerating delivery. In my projects, it enabled:

• 60% faster release cycles

• Early bug detection via automated tests

• Seamless rollbacks when failures occur"

Q: How does DevOps help developers?
A:
"DevOps bridges development and operations through:

• Collaboration: Shared ownership of deployments

• Automation: Eliminates manual repetitive tasks

• Feedback loops: Real-time monitoring improves code quality"

2. Architecture & Design Patterns

Q: Microservices vs Monolithic architecture?
A:

Q: Which design pattern would you use for complex software?
A:
"Depending on requirements:

• Domain-Driven Design (DDD): For business logic complexity

• CQRS: When read/write operations scale differently

• Observer Pattern: For event-driven systems"

3. Core Programming Principles

Q: Explain SOLID principles.
A:

1. Single Responsibility: One class = one purpose

2. Open/Closed: Extendable without modification

3. Liskov Substitution: Child classes replace parents

4. Interface Segregation: Avoid bloated interfaces

5. Dependency Inversion: Depend on abstractions

Q: Purpose of constructors?
A:
"Constructors initialize objects:

• Parameterized constructors set initial state

• Default constructors provide fallback values

• In C#, static constructors initialize class-level data"

4. API Development

Q: How to implement API security?
A:

• Authentication: JWT/OAuth 2.0

• Authorization: Role-based access control (RBAC)

• HTTPS: Encrypt data in transit

• Input validation: Sanitize all inputs

• Rate limiting: Prevent DDoS attacks

Q: Optimizing slow APIs with DB bottlenecks?
A:

1. API Level:

   • Pagination (LIMIT/OFFSET)

   • Caching (Redis) for frequent queries

2. Database Level:

   • Indexing critical columns

   • Query optimization (avoid SELECT *)

   • Connection pooling

5. Frameworks

Q: Security in Spring Boot?
A:

• Spring Security for auth (OAuth2, JWT)

• CSRF protection

• Password hashing via BCryptPasswordEncoder

• @PreAuthorize for method-level security

Q: Explain MVC.
A:
"Model-View-Controller separates concerns:

• Model: Data/business logic

• View: Presentation layer (UI)

• Controller: Handles user input and updates model/view"

6. Containerization

Q: Kubernetes basics?
A:
"Kubernetes orchestrates containers by:

• Managing deployments via pods

• Auto-scaling with HorizontalPodAutoscaler

• Service discovery via kube-dns

• Self-healing failed containers"

7. Personal Project Discussion

Q: Tell us about yourself and a project.
A:
"I’m a [Your Role] specializing in [Tech Stack]. Recently, I built [Project Name] using:

• Tech: C#/ASP.NET Core, Microservices

• Challenge: Scaling authentication service

• Solution: Implemented JWT with Redis cache

• Impact: Reduced auth latency by 40%"

8. Advanced Concepts

Q: Synchronous vs Asynchronous Tasks?
A:

• Synchronous: Blocks execution until completion (simple but inefficient for I/O)

• Asynchronous: Non-blocking (e.g., async/await in C#) improves throughput