I would recommend you start with : https://docs.splunk.com/Documentation/Splunk/8.0.5/Forwarding/Setuploadbalancingd#Specify_static_or_DNS_lists_for_receiving_indexers And set DNS A records. See Splunk Docs.  I won't go as far as to say never use a LB between UF and idx, cause i know with newer versions of UF and as i have worked with Splunk Eng, there are ways to make UF "LB Friendly" using newer version with the light event breaking UF does, but i would agree that if using traditional splunk2splunk protocol (s2s), just go all the way and rely on the application LB described in the doc above.  holler at me on slack (mattymo) if you want to chat more! ... View more