2.11 Self-test

What are the only two config requirements for brokers to form one cluster?

Why 5 ZooKeeper nodes rather than 3, when 3 already tolerates a failure?

Why is vm.swappiness=0 wrong, and when did it become wrong?

Your topic has 7-day retention but you find 17-day-old messages. Explain precisely why, and give two fixes.

log.dirs has three mounts; one is 95% full and the other two are near-empty. Why did Kafka do this?

Why does raising message.max.bytes risk both a stuck consumer and stalled replication?

acks=all is set and the producer got a success response, yet the message is gone. Explain the exact sequence.

What does RF++ mean and what two simultaneous events is it designed to survive?

Why does the broker need CPU at all, given it treats messages as opaque bytes?

Why is colocating another service on a broker a consumer performance problem specifically?

Give the outbound-network formula for sizing a broker's NIC. What term do people forget?

Rack awareness is configured and RF is 3, yet losing one rack took a partition offline. How?

Why does a ZooKeeper hiccup cause errors hours later during an unrelated controlled shutdown?

What are the current per-broker and per-cluster replica ceilings — and why is "replica" not "partition"?

You must set retention to exactly 24 hours for a compliance requirement, on a topic receiving 20 MB/day. What do you configure and why?

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