Please note that AX 2012 exams have already been retired:
www.microsoft.com/.../retired-certification-exams.aspx
The above mentioned exam is for Dynamics 365 for Operations Development introduction, which is quite different from previous versions. Your brief AX 2012 experience is likely not enough to pass without specifically training for AX 7. Have a look at the training material and courses available on the official link.
Here is a summary on what skills are measured: