Feedback network 1
This feedback network is very simple but has a few disadvantages. The DC value of the switching node (Vd) is regulated. Feedback capacitor from Vout helps feed forward the load transients to the feedback node to make the loop response faster for load transient responses.
Issues
If there is significant resistance after the switching node like a high ESR inductance or if there is a large load current then the output voltage goes down since it is not regulated directly.