What do the acks and replication settings control in Kafka durability?
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Quick Answer
Replication factor sets how many copies of each partition exist; acks controls how many replicas must confirm a write before it's acknowledged.
Detailed Answer
acks=all with min.insync.replicas>1 means a write is acknowledged only after replicating to the required in-sync replicas, surviving a broker loss. acks=1 acknowledges after the leader only (faster, can lose data on leader failure); acks=0 is fire-and-forget. Durability vs latency is the trade-off.
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Interview Tip
acks=all + min.insync.replicas is the durable config.
kafkaacksreplication