When a post stands out as rule-breaking, I'll log in to teh mod panel (which shows the IP address of every post) to deal with it. Sometimes the post in question will be from a familiar IP address/range that I've seen dozens of times before when dealing with rule-breaking posts, at which point I'll give the post less benefit of the doubt and maybe deal out a longer ban duration (not that it makes much difference)

I'm not monitoring teh mod panel and categorizing every IP into naughty & nice lists liek Santa-san if that's what ur asking