I have 3 Q2A instances running with a shared user base. I think I found how (in the related question) IP-banned users were able to register for new accounts - they used one of the other 2 sites.
So if I ban an IP on Site 1, that IP is not banned on Site 2 and they can register and post. Is there a way to copy IP bans to other sites automatically? In the docs for events there is one for when a user is blocked, but not for IPs.