Legally, what are potential employers allowed to ask previous employers?

I was just discharged from a job that I particularly didn't care for for "blatant insubordination". They did not give me any written or verbal warning and as far as I know, there is nothing on my record that would prove that I was insubordinate (in fact, the clients loved me). My question is: what... show more I was just discharged from a job that I particularly didn't care for for "blatant insubordination". They did not give me any written or verbal warning and as far as I know, there is nothing on my record that would prove that I was insubordinate (in fact, the clients loved me).

My question is: what can potential employers ask in regards to why I was discharged? I know they won't give me a good recommendation because they fired me so I guess I would just put "do not contact" for references on them? I'm really confused. :(
4 answers 4