The text is part two of a multi-part series detailing the integration of Apache Kafka with the Elastic Stack, focusing specifically on operational aspects such as capacity planning and monitoring when using Kafka and Logstash in production environments to handle large data volumes. The article emphasizes the importance of Apache ZooKeeper for Kafka operations, discussing how to set up a quorum configuration of ZooKeeper instances for stability. It addresses the significance of Kafka brokers in data retention and replication, explaining how the number of brokers correlates with data storage capacity. Logstash is highlighted for its flexibility in scaling horizontally and managing complex data transformation tasks, while also stressing the importance of careful capacity planning for external systems rather than Logstash itself. The text also covers Kafka's offset management system and methods to ensure message delivery guarantees, including handling potential data duplication. Monitoring tools such as Kafka's CLI tool, JMX, and the Elastic Stack's Kafkabeat and Metricbeat are recommended for tracking system performance and consumer lag. The article concludes by mentioning forthcoming updates in Kafka, including new security features, and promises further exploration of these features in the next installment.