# Discovery.zen.ping.unicast.hosts question

**URL:** <https://discuss.elastic.co/t/discovery-zen-ping-unicast-hosts-question/128324>\
**Category:** Elasticsearch\
**Created:** [April 17, 2018, 9:26am UTC](https://discuss.elastic.co/t/discovery-zen-ping-unicast-hosts-question/128324 "2018-04-17T09:26:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dao](https://avatars.discourse-cdn.com/v4/letter/d/a6a055/32.png) [@dao](https://discuss.elastic.co/u/dao)\
**Post date:** [April 17, 2018, 9:26am UTC](https://discuss.elastic.co/t/discovery-zen-ping-unicast-hosts-question/128324/1 "2018-04-17T09:26:50Z")

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Hello,

I am ready to add some nodes to my 1 node cluster. But to do so, I have to add the list of hosts to my discovery.zen.ping.unicast.hosts array. It is in the configuration file, that means I have to restart my node?

In the future, If I want to add some extra nodes, how can I do this without changing this discovery.zen.ping.unicast.hosts property (and therefore restart my nodes)?

regards

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**Author:** ![Bernt\_Rostad](https://avatars.discourse-cdn.com/v4/letter/b/3ab097/32.png) [@Bernt\_Rostad](https://discuss.elastic.co/u/Bernt_Rostad)\
**Post date:** [April 17, 2018, 10:06am UTC](https://discuss.elastic.co/t/discovery-zen-ping-unicast-hosts-question/128324/2 "2018-04-17T10:06:58Z")

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In theory you only need to identify one discovery host (node) for a new node to be able to join the cluster, but since that node may be down it's better to add several discovery nodes.

In the clusters I work with, where I use the minimum of 3 master eligible nodes, I always identify those 3 nodes in **discovery.zen.ping.unicast.hosts** but never any of the data nodes, since I will probably never have to add more master eligible nodes while I may continue to add data nodes to expand cluster capacity.

So once you've grown your cluster big enough to warrant a fixed number of master eligible nodes just add those nodes to your discovery settings and never change it again.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 15, 2018, 10:06am UTC](https://discuss.elastic.co/t/discovery-zen-ping-unicast-hosts-question/128324/3 "2018-05-15T10:06:58Z")

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