The traffic controller for user facing services in a logical cloud will manage the user facing dns names for these services in the external dns servers associated with the clusters in the logical cloud.

A project like external-dns appears to provide the basis for what is required.  The goal is to provide this function in the traffic controller, so dns server annotations would be provided as deployment intents.  Information about external IPs of individual clusters as well as the DNS server(s) associated with that cluster will also need to be available.