АДКАЗАЦЬ - Русский язык

first is incorrect but other ones can be used as ’’good night’’(like when you go to sleep) The last one can be also used as greeting if you work at night or very late

First sentens is not correct . ”Доброй ночи” и ”спокойной ночи”, обе фразы можно использовать, однако первая действительно немного архаична. Чаще используется фраза ”спокойной ночи”.

Good night is used as a greeting, and good night is used as a wish for pleasant dreams.

Hello. “Good night” (спокойной ночи = spokojnoj nochi) would be more correct. But we wish you good dreams and the phrase “good night” (доброй ночи = dobroj nochi). Both phrases are written the same in English. Both phrases are wishes for a good night and good things )))