Elasticsearch provides a discovery module, called Zen Discovery, that allows different Elasticsearch nodes to find each other.
By default, Zen Discovery achieves this by pinging ports 9300 to 9305 on each loopback address (127.0.0.0/16), and tries to find Elasticsearch instances that respond to the ping. This default behavior provides auto-discovery for all Elasticsearch nodes running on the same machine.
However, if the nodes reside on different machines, they won't be available on the loopback addresses. Instead, they will have IP addresses that are private to their network. For Zen Discovery to work here, we must provide a seed list of hostnames and/or IP addresses that other Elasticsearch nodes ...
