Ok, how many hops away does traceroute tell you the 216.23.15.143 addr is? and why is REMOTE_ADDR is set to 216.23.15.143 and SERVER_ADDR is set to 216.23.15.143 the same? (sorry I don't know this logging as I really don't do that much webserver stuff)
I would suggest sniffing the packets as they hit your web server and finding out what is going on.
"Nothing is sure but death and taxes" I say combine the two and its death to all taxes!