While in the middle of doing an SCCM 2007 to SCCM 2012 migration, my SCCM 2012 PXE Task Sequences would fail after the image had applied and the client was downloading and installing additional applications.
First thing I did before the image failed was to press F8 to load up a command prompt, then type in CMTrace so I could view the logs easily.
The log of interest was the cas.log which told me that the machine was unable to find any distribution points when locating the software. I knew the boundary was correct and that the boundary group was correct also.
The number of discovered DPs(including Branch DP and Multicast) is 0
Anyway, I double checked the boundary groups in SCCM 2012 and noticed that the SCCM 2007 running migration jobs automatically created a boundary group for the SCCM 2007 distribution point and assigned the boundaries I was using to it. This caused my clients unable to locate software to download and install additional programs.
I had migrated everything I needed from 2007 to 2012, so I simply stopped the 2007 migration job and deleted the automatically created 2007 boundary groups.
I then reimaged the machine and the cas.log looked good and could find the distribution point it needed to download the additional software for the Task Sequence.