Details: no matter if one is using the assisted installer or the agent based installer, there is no indication for the disconnected installation, to create a valid and reachable DNS record for the mirror registry, so that nodes can find that during the bootstrap installation

Documentation URL: https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html-single/installing_an_on-premise_cluster_with_the_agent-based_installer/index#understanding-disconnected-installation-mirroring