Is it possible to do GeoIP of private IPaddresses?

Hi I am a user of Splunk and Elasticsearch. I want to do GeoIP with private IPaddresses. There is information about it on the Elasticsearch forum (ex: [Private networks with GeoIP][1] This confirms that it is possible with Elasticsearch. But what about Splunk? Thank you [1]: https://discuss.elastic.co/t/private-networks-with-geoip/138099