While using the RUM Console to Add Computers From Active Directory, the following error is seen when attempting to browse outside of the domain to a source domain for example:
Also, attempting to use Active Directory Users and Computers from the RUM Console host and connecting to the same domain will produce this error.
This issue is caused by TCP/UDP port 88 traffic being blocked between the domain the RUM console server is installed in and the domain it is attempting to perform the LDAP query on. This port is required to be open for Kerberos authentication to succeed, which is the method of authentication being used by both impacted utilities.
This can be easily tested by performing a telnet test using port 88 to a Domain Controller in the impacted (usually source) environment on the RUM Console host.