Coordinating Node

Via the elasticsearch engineer 1 class regarding the Coordinating node it states:

• Configure your client to round-robin between multiple nodes
‒ avoid having single points of failure/creating hotspots
‒ do NOT send requests to dedicated master nodes

Where is this round-robin configuration set?

In the client connecting to Elasticsearch, e.g. Logstash, Beats, Kibana or any of the language clients.

Is there a specific yaml file?

Also what are the ramifications if the requests ARE sent to a dedicated master node?

It has to be set in the configuration of the various components that connect to Elasticsearch and they likely all have their own way of configuring it.

Dedicated master nodes are often quite small and should be left alone to manage the cluster in order to improve stability. If you send traffic to them you can overload them, which goes against the goal of using dedicated master nodes to improve stability.