When using Kafka Connect with sink connectors (like S3 Sink),each task is assigned one or more topic partitions. Thetotal number of partitions (6)isevenly distributedacross the available tasks (2). Thus, each task will handle3 partitions.
FromKafka Connect Documentation:
"Kafka Connect divides the topic partitions among available tasks. For example, a topic with six partitions and two tasks results in each task handling three partitions." Reference:Kafka Connect Concepts > Tasks and Partitions

According to the official Apache Kafka Connect REST API documentation, restarting a connector can be done at different granularities: connector-level, task-level, or both. By default, calling POST /connectors/
{name}/restart only restarts the connector instance, not its tasks.
To restart the connector and all of its tasks, the request must explicitly include the query parameter includeTasks=true. This instructs Kafka Connect to restart the connector and all associated tasks, regardless of whether they are currently running or failed.
Option B (onlyFailed=true) limits the restart to only failed tasks, which does not meet the requirement to restart all tasks. Option C restarts only the connector instance, leaving tasks untouched. Option D restarts a single specific task and does not restart the connector itself.
Therefore, the correct and officially documented REST request to restart the connector instance and all tasks is:
POST /connectors/s3-connector/restart?includeTasks=true
This ensures a full restart of the connector and its execution context across the Kafka Connect cluster.

The official CLI utility for consuming messages from Kafka topics is kafka-console-consumer.sh. It connects to the broker, consumes messages, and prints them to standard output.
FromKafka CLI Tools Documentation:
"kafka-console-consumer.sh is used to read data from a Kafka topic and write it to standard output." The other options are not valid Kafka CLI tools.
Reference:Apache Kafka Documentation > kafka-console-consumer.sh

To reset offsets for an existing consumer group, you must use the kafka-consumer-groups.sh tool with the -- reset-offsets and --to-earliest flags.
From Kafka Consumer Group Tool Documentation:
"You can use the kafka-consumer-groups tool to reset offsets for a consumer group. This is required if the consumer has already committed offsets." Setting auto.offset.reset=earliest only works if no committed offset exists.
Starting a new consumer with the same group won't reset offsets.
Retention settings don't affect committed offsets.
Reference: Kafka Consumer Group CLI Tool

The onCompletion() method of Kafka'sCallback interfaceis executedonce the broker acknowledgesthe message. This includes success or failure, and it isinvoked asynchronouslyby the producer.
FromKafka Java Client API Documentation:
"The onCompletion method will be called when the record sent to the server has been acknowledged, or when an error occurs." This ensures thatthe record was sent and acknowledged, not just added to a batch or local buffer.
Reference:Kafka Java Client API > org.apache.kafka.clients.producer.Callback