What Is The Right Response To “How Do You Do?”

So yesterday I learnt that the correct response to “How Do You Do?” is “How Do You Do”.
It made no sense to me because I thought the logical response would be “fine” or “good” or stuffs like that,that is why I have brought this to Naijaoadites to clarify.
So professors in the house,let us know which is the correct response to “How Do You Do?”.