Know or Don't Know

The question that has been plaguing me is what is that I know that I know and I know that I dont know and similarly what is that I dont know that I know and I dont know that I dont know. Going deeper what is that I know that I dont want to know and I know that I want to know coupled with what is that I dont know that I dont want to know and I dont know that I want to know.
The statement above might be very confusing but I guess I have made sense.
Also, as a side note ever wondered that knowledge could also be harmful. I guess that is why the proverb "Innocence is bliss". Knowledge can be both boon or bane but I guess it also depends upon how one uses the knowledge too.