@tuxnet, please clarify what you mean by "AD doesn't support Kerberos". AD does in fact use Kerberos for authentication under the covers.
When a separate MIT-KDC is used, the usual design is to use it to store the host and service principals associated with the Hadoop cluster. The user principals are stored in AD, and a one-way trust is established between the AD domain and the MIT-KDC realm so that users in AD can access cluster services (but not the other way around).
This HCC article discusses one-way trusts between MIT-KDC and AD.