If you bake bread properly all the yeast will die, but it is pretty easy to underbake it, especially if your new at it.

I found the main reasons I underbaked in the beginning were opening the oven to check it, stopping early because it looks dark and the most common way was not letting it cool before cutting into it. (Bread keeps cooking on the inside after you take it out and when you slice it too early it looses it's internal temperature too fast)

Toasting it will kill of most live yeast. Another really good tip I don't see in recipes is while your bread is still warm but not hot enough to melt a plastic bag, wrap it up in the bag and the remaining moisture in the bread will soften the crust.

Nothing worse than a sharp, rock hard crust around a slice of soft bread.. IMHO.

Good luck!!