Rather than use 3rd party websites, we'd like to use Splunk to geolocate an address that may not yet be indexed. Similarly, we have many network ranges, so we'd like to search an arbitrary address to find at which of our locations it resides. The ranges are in an index, but not all gazillion addresses we own.
Splunk has the existing "| iplocation" command which does this at search time using its local copy of Maxmind's "free" GeoLite2 database.
With the correct scripting tools, it's "not difficult" to add your own ranges to the GeoLite2 database and have them show up in the output of the "| iplocation" command just like any external IPs might.