Many forums feature an IP ban feature. This feature allows an administrator to deny access to a member/internet user to the forums based on their IP address. Several forums also have the feature to ban an IP range, which allows an adminitrator to disallow geographies from accessing their forums.

In addition to IP bans, several forums implement bans on DNSBL (Domain Name Server Blackhole List). To read more about what DNSBL's are, please visit: http://en.wikipedia.org/wiki/DNSBL.