These IPs are evil or have been used for evil actions (such as adding spam entries to our school data base). IPs that are already in the (hard coded) black list have been removed here. You can find them in the history if this page. Multiple records are prone to get into the black list, next.
(IPs that are used for blocking have been removed from this blacklist)
And this is a way to know more about the DNS names or their providers:
$ for i in `cat ip-blacklist`; do host $i ;done