When adding domain names to be removed from the Device Alias leave off the preceding '.'.
For example instead of '.ca.com' use 'ca.com'.
This is done in the Console > Config > Discovery > DNS domain(s) to remove from alias:
Also when adding multiple names like ca.com, communities.ca.com, support.ca.com, put ca.com at the end of the list.
Putting ca.com first could result in Device Alias names like cisco124.communities or cisco125.support.
Also, spaces are a weird one. In our installation, if we put in the list
of domains with only a comma as a separator, after saving and coming back
to the config, the spaces are put back in there.
This document was generated from the following discussion: 'DNS domain(s) to remove from alias'