The IPs assigned to the CDS authentication endpoint are:
These should be whitelisted in a customer's firewall for the CDS authentication endpoint to be reachable. Endpoints for the actual CDSes cannot be assigned static IP addresses (and hence cannot be explicitly whitelisted in a firewall). The best course of action for that would be to whitelist all the IP addresses in the US-WEST-1 zone, described by the official Amazon list found here https://ip-ranges.amazonaws.com/ip-ranges.json.
Splunk Mint SDKs use a unique URL for each one of you apps, based on your API key. So if you API key is, for example,
deadc0de, the domain that should be allowed through the firewall is:
However, since the endpoints that serve these URLs are behind a load balancer, unfortuinately there is no specific IP range that you can allow.