Hi Zamoraw,
Please note that at present, Splunk Insights for Infrastructure only supports deployment in a clean environment. If you're running Insights for Infrastructure, this question is a bit moot. If you're running the App for Infrastructure, we only support single-node deployments, so your Instance would be all the things.
If this is a general question (how do I tell what role my Splunk node is playing), You may be able to determine this via the Monitoring Console: http://docs.splunk.com/Documentation/Splunk/7.1.1/DMC/DMCoverview
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