Cloudera Manager is designed to be resilient to minor name resolution misconfigurations, where the same host may be a member of multiple subdomains but all names resolve to the same physical host. This means that all short (i.e. unqualified) host names must be unique when added to Cloudera Manager.
Thus, the following hosts should not be added to the same Cloudera Manager managed cluster:
host1.subdomain1.example.com (IP: 192.168.1.1)
host1.subdomain2.example.com (IP: 192.168.2.1)