Can you use the ignore functionality on an alias? Just curious, I see that option on a username, but not on an alias.

You can only ignore the real username.

Thanks for information. So, if I'm understanding you correctly, in the link below, the alias claims she is on ignore. Since this can't happen, this supposed OP must really know the alias's username to use the ignore functionality?  

Yes. The username & alias are linked. It can be time consuming but if you put a username on ignore ALL their posts including when they are using their alias will come up on the boards as "this user is ignored" & you won't be able to see what they posted. If you log off you will be able to see it & who the poster is.