Yosemite clients are not being enrolled upon manual registration, the error appears:
"The Domain Name is incorrect or the domain controller is not online. Couldn’t find the domain “firemountain.local” I am able to ping out domain controllers and everything else if functioning properly on the macs."
AD domains named XXX.local are not supported in OS X 10.10.
For more information, please refer to Apple KB: https://support.apple.com/en-us/HT203136.
In short, there are critical problems in OS X with kerberos authentication, which are in use in some Parallels Mac Client scenarios, such as registration and NetBoot.
Moreover, OS X 10.10 behaves inconsistently in these cases, so even if you think it works ok, it will be failing unexpectedly.
On the Mac, add your DNS Server in the hosts file (/etc/hosts).
If it does not help, as the issue is caused by known problem in OS X, could you please check the issue with another domain (not .local)
Please understand that we need to troubleshoot issues using the recommended infrastructure setup.