DRBL is like (is) a diskless netboot server. This allows user computers to boot from the network without a local hard drive. The FOG Project does not supports. The FOG Project purpose is to capture and deploy disk images between the FOG server and target computers hard drive.
I can tell you that the FOG Project uses many of the same resources and DRBL. You can make FOG server act like a DRBL server. I wrote an article on how to make something similar to DRBL. Understand that the FOG Project developers do not support changing the function of FOG. But I can tell you it works. You will need a Linux Live OS that supports network booting and this tutorial: https://forums.fogproject.org/topic/10944/using-fog-to-pxe-boot-into-your-favorite-installer-images