A long time ago we added the external api and ingress records to our internal coredns instance to enable PoC deployments without modification to the sitewide DNS infrastructure (which may require a lengthy request process to change). This is not intended for production use - that would require all external users to point their DNS resolver at one of our internal DNS servers and they're not intended for general use like that. As a result, this ability is not currently documented anywhere, at least that I'm aware of. We have a request in https://issues.redhat.com/browse/RFE-4002 to document the internal records so there's an official statement about the existence of these records and their intended use.

Since this isn't supported for production, I think this should go into a KCS article. This story is to track writing that content.