Kafka medium
Under which specific circumstance is a Follower node physically removed from the 'In-Sync Replicas' (ISR) list?
- A If it is hosted on a different subnet than the Leader node.
- B If it fails to 'catch up' (fetch the latest leader offsets) within the configured `replica.lag.time.max.ms` window.
- C If it is currently serving more than 100 consumer fetch requests per second.
- D If the administrator manually marks the node as 'Suspicious' in the dashboard.
Answer: B. If it fails to 'catch up' (fetch the latest leader offsets) within the configured `replica.lag.time.max.ms` window.
The ISR list contains nodes that are 'caught up'. If a node is too slow or its network is flickering, it is kicked out. This ensures that a single dying node doesn't permanently block the cluster's ability to accept new writes (when `acks=all` is used).
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