Build a Software Engineer Resume that cracks FAANG Interviews

This is a classic 'System Design' question for Senior roles. **1. Requirements:** Supports 100M writes/day? Short expiration? **2. Database:** NoSQL (DynamoDB/Cassandra) is better than SQL here for write throughput. **3. Algorithm:** Use Base62 encoding to generate 7-character strings. **4. Scale:** Add a Cache Layer (Redis) to store popular redirects (80/20 rule). **Key Tip:** Don't just list tools; explain *why* you chose them based on CAP theorem constraints.

**Context:** We were rushing a feature that had a security vulnerability. **Action:** I didn't just say 'no'. I estimated the cost of a data breach vs. the revenue of launching on time. I proposed a 'Feature Flag' phased rollout to mitigate risk. **Result:** The PM agreed to delay by 2 days, and we saved $50k in potential compliance fines. **Why this works:** It shows 'Business Acumen' and 'Ownership'—traits highly valued in US tech.

**First Step:** Don't guess. Use a profiler (Datadog/NewRelic) to find the bottleneck. **Common Culprits:** N+1 Query problem (database fetching in a loop), lack of Indexes, or heavy payload size. **Fix:** Implement Pagination (Cursor-based is better than Offset-based), Add a Redis Cache for read-heavy data, or use GraphQL to fetch only required fields.

Think of `useEffect` as a synchronizer. The code inside runs *after* render. The dependency array `[]` tells React *when* to re-run it. - No array: Runs on every render (Dangerous!). - Empty array `[]`: Runs once on mount (Like componentDidMount). - `[prop]`: Runs only when 'prop' changes. **Trap:** Forgetting to clean up subscriptions in the return function leads to memory leaks.

This tests 'Full Stack' understanding. 1. **DNS Lookup:** Browser checks cache -> OS cache -> ISP DNS -> Root Server. IP is found. 2. **TCP Handshake:** SYN, SYN-ACK, ACK. Connection established. 3. **SSL/TLS Handshake:** Encryption keys exchanged. 4. **HTTP Request:** GET request sent to server. 5. **Load Balancer:** Routes traffic to a healthy server instance. 6. **Response:** Server sends HTML. Browser parses DOM tree + CSSOM tree -> Render Tree -> Paint.