Recently we tried to join an Cisco ISE instance to Active Directory without success. The problem seemed to be because of the length of the ISE host name. Even though the system supports host names up to 19 characters long, we couldn’t add the ISE to AD until we shortened the name to be maximum 14 characters.
Another one of those undocumented “features” that I wish I have read about before getting stuck. I wish this short post is indexed so that other people find out and gets a push in the right direction because of it.