I have a question about how many licenses I need. We have a new machine with only two physical processors.  I'm in the process of buying Windows Server 2012 Standard. I want the two run two VM's. One VM will be running Windows 2012 w/ Exchange Server 2013 and the other will be running Windows 2012 Server w/ AD, DNS and .  Do I need to buy one license for the physical machine and then two more, one for each VM?  I read that each license allows for up to two VM so I'm a little confused on if I need one license or three.    

With Server 2012 Standard, you can install 2 "free" Windows Server VM instances with the same license on the host computer. 

However, this is only the case if you are only running the Hyper-V role on the host.  If you install other roles on the host server like AD, DNS, DHCP, etc. you forfeit the "free" Windows Server VM instances.