AWS Key Services Every Developer Should Know — A Practical Guide

Rashmi Roy — Thu, 11 Dec 2025 03:37:00 +0000

This article summarizes the essential AWS services you must know to build, deploy, secure, and scale modern applications.

Compute

EC2 — VM instances with OS-level control.
Lambda — Event-driven serverless compute.
ECS/EKS/Fargate — Container orchestration and serverless container runtime.

Storage

S3 — Object storage for binaries, logs, backups.
EBS — Block-level storage for EC2.
EFS — Distributed NFS file system.

Databases

RDS — Managed SQL engines (MySQL, PostgreSQL, etc.).
DynamoDB — Fully managed NoSQL key-value database.
ElastiCache — Redis/Memcached for caching.

Networking

VPC — Isolated cloud network environment.
Route53 — DNS and traffic routing.
API Gateway — REST/WebSocket interface for serverless and microservices.

Security

IAM — Identity & access management.
KMS — Encryption key management.
Secrets Manager — Secure credential storage.
Shield/WAF — DDoS and app-layer protection.

DevOps

CodePipeline — CI/CD orchestration.
CloudWatch — Monitoring and observability.
CloudTrail — Full audit log for the AWS account.

Final Thoughts

Mastering these services provides a solid foundation for building scalable cloud-native applications on AWS.

10 React.js Interview Questions That Stumped Me (With Answers)

Rashmi Roy — Sat, 12 Apr 2025 04:36:34 +0000

Interviews are like open-book exams where the book is in your brain — and sometimes, mind blanked out. 😅

After 7+ years in frontend, I thought I’d seen it all… until these React.js questions made me pause.

I’m sharing them with clear explanations so you don’t get stumped like I did. Let’s go! 👇

1. 🔄 What's the difference between `useEffect(() => {}, [])` and `useLayoutEffect(() => {}, [])`?

Hint: Timing matters.

✅ useEffect runs after the DOM paints.

✅ useLayoutEffect runs before paint — can block rendering.

Use useLayoutEffect only when DOM measurement or mutation is needed.

2. 🧠 Why is `key` prop important in lists?

It helps React identify which items changed, are added, or removed. Without a key, React may re-render unnecessarily.

3. ⚡ Can you explain React reconciliation?

React compares the new virtual DOM with the previous one. It tries to minimally update the actual DOM using keys and diffing.

4. 🌀 What is a closure, and how can it cause bugs in React hooks?

Closures remember variable states. In hooks, outdated closures can cause stale state bugs, especially in setInterval or event handlers.

5. ❓ What's the difference between controlled and uncontrolled components?

Controlled: React manages the input state (value, onChange)
Uncontrolled: DOM handles it via ref

6. 🧪 How would you test a component using React Testing Library?

Use:

render(<MyComponent />);
expect(screen.getByText(/hello/i)).toBeInTheDocument();

7. 🚀 What is code-splitting, and how do you implement it in React?

Using React.lazy() and Suspense to load components only when needed, improving performance.

8. ⚙️ What happens if you update state inside useEffect?

It can cause re-renders. Be cautious of infinite loops if dependencies aren't correctly defined.

9. 🛑 What are some common mistakes with useState?

Initial value not set correctly

Forgetting it’s async

Updating state based on current state without using callback form:

setCount(prev => prev + 1);

10. 👻 Why do people still use Redux if we have Context API?

Redux offers predictable state, middleware support, and better dev tools. Context is fine for low-frequency updates, but not large-scale state.

💡 Final Thought
Interviews test your thinking more than just syntax. These questions helped me level up, and I hope they help you too.

What’s the trickiest React question you’ve faced? Drop it below! ⬇️

DEV Community: Rashmi Roy