When you start your ElasticSearch nodes, one of the first things ElasticSearch does is it looks for a master node that has the same cluster name and is visible to them. If a master is found, the node gets joined into an already formed cluster. If no master is found then the node itself is selected as a master. The process of forming a cluster and finding nodes is called discovery . The module responsible for discovery has two main purposes—electing a master and discovering new nodes within a cluster. In this section we will discuss how we can configure and tune the discovery module.
By default, without installing additional plugins, ElasticSearch allows us to use zen discovery, which provides us with multicast and unicast discovery. In computer networking terminology, multicast is the delivery of messages to a group of computers in a single transmission. On the other hand we have unicast, which is the transmission of a single message over the network to all possible...