At what age should my rottweiler start to bark?

Yep defiantly normal my little pup puts so much energy in her bark she falls down!

Yes, this is completely normal.

Most puppies begin barking in the whelping box. But if the puppy is barking and showing an aggressive stance, it is time to get him to a puppy training class and learn some leadership skills because you have your work cut out for you.

That's normal. Barking, growling, grunting etc.. is how dogs communicate. There's nothing to worry about with your puppy. :]

It's completely normal, they can start barking after about 2-3 weeks old.

I just got a little 8 week old american rottweiler and he already knows how to bark is this normal?

yes, it happens fast naturally but it is very possible he already learned from his mother or so