Elasticsearch's discovery plugin is designed to maintain up-to-date information about the cluster state across nodes, primarily through the ZenDiscovery plugin, which manages master election, cluster state updates, node discovery, and fault detection. The plugin operates by implementing the discovery interface, which includes methods for publishing cluster states and identifying the local node, ensuring all nodes in the cluster share the same view. Alternatives to ZenDiscovery, such as LocalDiscovery and EC2Discovery, provide different approaches depending on the deployment environment, while custom plugins can be developed if ZenDiscovery's capabilities are insufficient for specific needs. The article suggests that understanding the intricacies of leader election and consensus in distributed systems, such as through Paxos, can inform plugin development and that leveraging existing tools like ZooKeeper and its curator frameworks can prevent unnecessary reinvention.