Build it: Consistent Hashing
An interactive sandbox where you drag real components together, connect them, and run a live traffic simulation to see where the design breaks.
Challenge: Place shards behind the <strong>hash ring</strong>. Each request maps to one shard with <code>hash(key) % N</code>. Then kill any shard with the red X. Only 1 out of every N keys is affected. That is the win of consistent hashing.