[Help] How Does Banning Work?

Hi there, I play MW2 using the RepZ client and have been using a hack that for a long time went undetected, but recently they detected it and banned me from RepZ servers. So I was wondering, by which method do they ban anyway - name, IP Address, MAC Address, etc. And any way to get around it / get unbanned?

One of the players on a different server I was talking to recommended making a post on this site, so here it is! Any help is appreciated and thanks in advance!