Load Balancing
Difficulty: Easy | Topic #4
What to Learn
Layer 4 (transport) vs Layer 7 (application) load balancers, routing algorithms (round-robin, least connections, IP hash), sticky sessions, health checks, and geographic load balancing.
Resources
- Hello Interview: Networking Essentials ↗
- Gaurav Sen: System Design — Load Balancers ↗
- ByteByteGo: Top 6 Load Balancing Algorithms ↗
Covered by Problems
| Problem | Difficulty | Link |
|---|---|---|
| URL Shortener/Bitly | Easy | → |
| Local Delivery | Easy | → |
| YouTube | Medium | → |
| LLM Service (ChatGPT) | Hard | → |
Key Concepts to Master
- L4 vs L7 load balancers and when to use each
- Round-robin vs least-connections vs IP hash algorithms
- Sticky sessions and why they complicate horizontal scaling
- Health check mechanisms (active vs passive)
- Global load balancing with GeoDNS