Concept explanation
Scaling a backend is not only adding servers. Traffic has to be distributed in a way that respects capacity, health, and active work.
All games
Load Balancer Challenge
Route simulated traffic across backend servers using round robin, weighted round robin, least connections, and random strategies.
- Concept
- Load balancing strategies
- Difficulty
- Intermediate
- Play time
- 6-10 minutes
- Path
- Production Reliability
practice/load-balancer-challenge Stability score Play, get feedback, save local progress, and optionally submit a leaderboard score.
Playable game area
Use the controls below. Feedback appears immediately, and final scores are stored locally.
Leaderboard
Top 10 submitted scores. No account required.
Loading leaderboard...
Finish the game to load your latest local score.
Learning objectives
- Compare routing strategies under changing server capacity.
- Understand overload, latency, and health-aware routing.
- Connect horizontal scaling to practical traffic distribution.
How to play
- Review server capacity, current connections, and health.
- Choose a load balancing strategy for the next traffic burst.
- Watch latency, overload, and throughput update after each round.
Scoring
- Stable throughput adds points.
- Overloaded servers reduce your score.
- Choosing a strategy that fits server health and weight earns better results.
Backend concept notes
Load balancers distribute traffic across multiple backend instances. The best strategy depends on request cost, server capacity, health, and whether user sessions need stickiness.
Round robin is simple, weighted routing handles different capacity, and least connections reacts to uneven active work.
Common mistakes
- Treating all servers as equal when they have different capacity.
- Ignoring server health during traffic spikes.
- Using sticky sessions without considering uneven load.
FAQ
Short answers for how this game fits backend interview and study practice.
Why is random routing included?
Random routing is simple and can work surprisingly well at scale, but it can be unstable in small simulations or uneven server pools.
What are sticky sessions?
Sticky sessions route a user back to the same backend instance, which can help session state but may create uneven load.