Can an external Client directly query a data node?

Hello everyone,

I followed this article to configure certain nodes in my cluster as data nodes.

I then ran this API call GET /_all/_search on the data node and was able to receive a response.

So wanted to check if this result is an expected behaviour or not. I was under the impression that the query to a data node can only be performed by a master/coordinating-node and not by an external client.

Thanks in advance,
Ashutosh.

Perhaps read about the different types nodes here

Data nodes can be directly queried, a data node is also implicitly a coordinating node.

Typically master nodes are not directly queried, that is not best practice.