CCDAK Exam Dumps : Confluent Certified Developer for Apache Kafka Certification Examination

In this case, because the offset 3000 has been committed and all the messages between 0 and 3000 have all been processed, it is okay not to have committed offset 2000. The right answer is to do "nothing", this behaviour is acceptable

One consumer per partition assignment will keep 5 consumers idle.

Keys are necessary if you require strong ordering or grouping for messages that share the same key. If you require that messages with the same key are always seen in the correct order, attaching a key to messages will ensure messages with the same key always go to the same partition in a topic. Kafka guarantees order within a partition, but not across partitions in a topic, so alternatively not providing a key - which will result in round-robin distribution across partitions - will not maintain such order.