How to detect what face a ray hit?

So I have a script that casts a ray, and want to know how I would be able to tell what face of an object the ray hit? Like if the ray hit the front of a brick, how would I edit the script so that the script will know that the ray hit the front?

It depends on what shape that ray hit. It's pretty advanced, thought here is someone else's script: http://pastebin.com/sXZ9FTNz

Try to understand how it works, and you will be able to make it.