Welcome to the Centrify Community.
Can you clarify if your Kerberos realm trusts AD? What kind of trust?
What version of CentrifyDC? (adinfo -v) You must be at 5.3.1 if you want to take advantage of "host name to Kerberos mapping"
If not, then you are looking at a mixed Kerberos deployment, please check out this article: http://community.centrify.com/t5/Community-Tech-Blog/HOWTO-Use-Centrify-in-Mixed-Kerberos-Environments/ba-p/21326
.... and you're back. By reading the article now you understand that you have to specify alternate locations for the keytab, make sure that DNS will resolve, etc. This works like a charm.
Good luck!
R.P