# Elasticsearch Client node type? **URL:** \ **Category:** Elasticsearch\ **Created:** [December 8, 2017, 2:45pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862 "2017-12-08T14:45:58Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![prachiwadekar](https://avatars.discourse-cdn.com/v4/letter/p/6f9a4e/32.png) [@prachiwadekar](https://discuss.elastic.co/u/prachiwadekar)\ **Post date:** [December 8, 2017, 2:45pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/1 "2017-12-08T14:45:58Z")
Hi, In elasticsearch 2.4.5, what type of client does a CLIENT node use to communicate with the DATA and MASTER nodes? Does it use a Node client and try to connect to every other node in the cluster? Or does it use a Transport client ? Thanks! ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [December 8, 2017, 3:02pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/2 "2017-12-08T15:02:44Z")
A Client Node is part of the cluster. It uses the Transport Layer to communicate with other nodes. He is aware of the whole topology so it connects directly to the right clients. It uses in that sense a Node Client. ---
**Author:** ![prachiwadekar](https://avatars.discourse-cdn.com/v4/letter/p/6f9a4e/32.png) [@prachiwadekar](https://discuss.elastic.co/u/prachiwadekar)\ **Post date:** [December 8, 2017, 3:10pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/3 "2017-12-08T15:10:36Z")
Thanks @dadoonet. What happens In the case that a CLIENT node is able to connect to a Master node but not to some other node in the cluster? ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [December 8, 2017, 3:23pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/4 "2017-12-08T15:23:10Z")
That should never happen IMO. But what is your exact concern ? ---
**Author:** ![prachiwadekar](https://avatars.discourse-cdn.com/v4/letter/p/6f9a4e/32.png) [@prachiwadekar](https://discuss.elastic.co/u/prachiwadekar)\ **Post date:** [December 8, 2017, 3:37pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/5 "2017-12-08T15:37:59Z")
@dadoonet I faced a scenario where we had incorrectly setup the firewall rules and a CLIENT node was able to join the cluster as it had access to the MASTER node but was not able to connect to one of the DATA nodes. This causes periodic exceptions to be logged when debug mode is enabled: SendRequestTransportException[[es-2a][172.22.70.25:9300][cluster:monitor/nodes/info[n]]]; nested: NodeNotConnectedException[[es-2a][172.22.70.25:9300] Node not conn ected]; I am not able to figure out why this action is invoked: cluster:monitor/nodes/info[n]? ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [December 8, 2017, 6:23pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/6 "2017-12-08T18:23:38Z")
I see. Did you fix the firewall problem? It's important that a Node in general (whatever its purpose) can always join the whole rest of the cluster. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [January 5, 2018, 6:23pm UTC](https://discuss.elastic.co/t/elasticsearch-client-node-type/110862/7 "2018-01-05T18:23:53Z")
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