As a Data Engineer in Germany 🇩🇪 one thing I learned: companies care more about what you can BUILD than what you can list on a CV. If you’re serious about Data Engineering, build these 5 projects: Batch ETL Pipeline Real-time Kafka Pipeline Spark Data Processing Project Cloud Data Warehouse End-to-end Analytics Pipeline 5 strong projects > 50 certificates.

Why does a 6-digit OTP expire in 30 seconds? Why not 5 minutes or 10 minutes?

Why can a 100GB file compress to 5GB, while another 100GB file barely shrinks? What makes data compressible?

Why can 100 concurrent users slow down an API more than 10,000 requests sent one after another? Isn’t the total workload what matters?

Interviewer: YOUR DATABASE GOT SLOWER AFTER DOUBLING RAM. Before: 300ms. After: 2.4 seconds. No query changes. What would you investigate?

Why does a 5GHz Wi-Fi network sometimes perform worse than 2.4GHz? Isn’t 5 supposed to be faster?

Why can a 1MB JSON file use 10MB of RAM? Where does the extra memory go?

Whoever invented QR codes deserves a lifetime achievement award. That little square is pure genius.

Why can a 10-line SQL query run slower than a 1,000-line query? Does code length mean nothing for performance?

Interviewer: YOUR AI AGENT HAS 99% TOOL-CALL SUCCESS BUT ONLY 60% TASK SUCCESS. Every API responds correctly. No infrastructure failures. Where is the reliability breaking down?

Why can a 7B parameter AI model sometimes outperform a 70B model? Does 10× bigger not mean 10× smarter?

Why does a 500GB SSD show only around 465GB? Where did the missing 35GB go?

Why does a 3GHz processor sometimes outperform a 4GHz processor? Aren’t higher numbers supposed to mean faster?

This Dussehra, I performed Ayudha Puja for my entire AI team. 😂🙏

Why does 100 Mbps internet download at only 12.5 MB/s? Where does the remaining speed go?

Interviewer: YOUR DATABASE IS FASTER WITH 1 USER THAN 100 USERS. Single query: 20ms. Under load: 4 seconds. CPU stays below 30%. What’s causing the slowdown?

Open-source software changed how developers build products. Open-weight AI is making powerful models more accessible. Could the biggest AI innovation come from outside Big Tech?

Would you trust an AI doctor?

Interviewer: YOUR RAG SYSTEM IMPROVED RETRIEVAL ACCURACY BUT ANSWER QUALITY DROPPED. Recall@10: 85% → 97%. Answer accuracy: 91% → 72%. How can better retrieval produce worse answers?