I went this route: http://www.jadota.com/2013/01/installing-samba4-on-ubuntu-12-04/
The Samaba4 AD setup gave me all the AD and DNS functionality that I needed, I am even able to join workstations to the domain and managem them using the MS AD tools (including the DNS snap in)
It is lightweight and quick to setup. Of course using local accouts work, I just wanted to have the AD/DNS stuff handy in my lab.