(Image removed from quote.)
I've confirmed.
V1 is 0
V2 is 0
V3 is 6V
basically the reverse bias allows no current in the circuit (There might be some, but let's assume it is a perfect diode and blocks out all current)
using Ohms law on the resistor we have V = IR when I is 0 there is 0 V
for the forward bias diode we can not use ohms law as it does not have a linear relationship.
Looking at the graph of a diode, we are only dealing with the positive half of the graph (Since forward bias implies positive and reverse bias implies negative)
when I is 0 we see that V = 0 Hence V2 = 0
However at V3 we see its a reverse bias diode, again looking back at diode graph, we are only dealing with the negative half. Since the battery is 6V and when I = 0, the voltage can be anything for the reverse diode, so the potential difference is 6 V.