Base JK2 doesn't have automatic IP logging. Jedi Academy (admin)Mod for JK2 has automatic IP logging when clients connect (mlog_ClientConnect: name ->IP address). That's one of the nice, benign, non-abusive features of admin mods. You were probably watching the console of a JK2 server running Jedi Academy Mod.
There is no equivalent admin mod for JA at this time (to the delight of those who hate them).
Well... i found the forums where chosen one himself talks about the mod (the Jedi Academy Reloaded mod for JA) and from what ive read theres going to be all kinds of goodies! For example someone suggested that the admin should have a super vehicle that no one can kill This is great... oh yeah, im not an admin I just suggested equality for all, and that he should take out some of that crap he has in the mod, like sleeping, silencing, slapping... etc but keep the important stuff... no reply... and its been over a month, no one has posted at all