What kind of snake is this?

My dog was barking at it in the yard a little bit ago. I wouldn't let her get any closer. But I'm just wondering kind of snake it is. Last time there was a snake in the yard, we figured it might've been a copperhead and my dog tried to become playmates with it. I know that usually slender headed snakes aren't dangerous, but still. It was a brownish red color, with black spots and it looks like a yellow belly.