the changes regarding
cmk-agent-ctl register are now officially documented here:
As far as I know only the site to which the agent is registered can poll the agent. In a distributed environment with disabled Setup this means the registration hast to be done with the remote site. Will then the host created twice on master and on remote site or how does that works?
The remote site will accept the request to create a host from the controller. The central site will then process that request, and decide if a host should be created on the remote site. The created host and its configuration will then be synced to the remote site.