MD is no longer qualified for RN test, at least in California. But foreign nurses still can take NCLEX-RN test if they are qualified.
For nurses outside US, they must pass CGFNS before they find a sponsor(agency or hospital). If they are in US, CGFNS is waived in California and New York state, they may take NCLEX-RN directly after their education is certified by Board. In other states, CGFNS is also required, same as in foreign countries.