I know that there are three types of banning in the forums are:
1- banned by IP
2- banned by account
3- banned by MAC address
My question is about banned by IP
If I have a home network (router and 3 computers)If a site Prevent one computers. Prevention will be to All in a home network.
In other words, the prevention for router
I take it your question is "if one computer gets banned, will all three get banned"
go to
www.whatismyip.com - That is your outside address that is how you communicate on the web. If that address gets banned, its game over (unless you have a way to change it which is another topic)
If you are using a router to use NAT, all the computers inside have the same outside address, while internally its usually 192.168.x.x or 10.x.x.x give or take (which the outside world cares nothing about). So if a forum bans your IP, it would be your outside single address associated with your router. All computers connected via that router would be unable to access it. MAC address have to do with the hardware which a website doesn't contain. Its more of a local issue. Bans are one of the first two methods.
Hope that helps some,
-Scott