A chat has 50 WebSocket servers. A message for Bob arrives at server 1, but Bob is connected to server 7. How does it reach him?

Options

• ✗ Server 1 opens its own connection to Bob's phone
• ✓ Look up Bob's server in a connection registry (or a pub/sub channel per user) and forward it there Correct
• ✗ Broadcast it to all 50 servers and let each check
• ✗ Bob's client polls server 1

Why

Each server records which users it holds (e.g. in Redis), or subscribes to a channel per connected user. Broadcasting works for a handful of servers but multiplies traffic by the server count.

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