I also have 0 tolerance for violence. At his age he is definitely able to know right from wrong. Few months ago I had a 3 year old boy start here. He lasted 2 days because he hit the other kids and didn't think he had to follow my rules and told me that he doesnt have to listen to his mom so he sure wasn't going to listen to me.

It's hard for parents to work on these issues at home when a lot of times they have no siblings where at daycare there more kids around. Good luck I hope you can straighten him out!