Point this application's customer domains at your own infrastructure

Available on every plan (it is how a Connect-only plan gets domains that serve). cname_target must be a public hostname that is not the platform edge; send "" to go back to the edge. apex_ipv4 (up to 4 public IPv4 addresses) is what root domains get on DNS providers with no ALIAS-style record; without it such roots cannot be pointed at a hostname and POST /domains:check reports apex_strategy: unsupported.

Applies to new connections and to domains still waiting for DNS (pending or failed, with no records supplied or written for them). Connected domains keep the routing they connected with (their routing field); move one with POST /v1/connections/{id}:retarget. existing_domains in the response counts both.

Refused (400) when cname_target resolves to the platform edge (a CNAME to it, or one of its addresses), or when apex_ipv4 lists an edge address: such domains would verify but never be served. A cname_target that does not resolve yet, or a target with no apex_ipv4, is accepted with a warnings entry. Every change is recorded in the audit log (app.routing_set, app.routing_cleared).