in-addr.arpa?

Why would 216.136.44.104 do something like this? 10 sl-inetconn-1-0-0-T3.sprintlink.net (144.228.207.46) [AS 1239] 200 msec 204 msec 208 msec 11 pa1-atm0-6-bbr01.alby.twtelecom.net (207.250.101.2) [AS 4323] 244 msec 264 m sec 248 msec 12 pa1-atm0-5-acr01.alby.twtelecom.net (216.136.44.242) [AS 4323] 256 msec 252 msec 252 msec 13 learnl-ppp-1130-09-u242.alby.twtelecom.net (207.250.24.30) [AS 3857] 256 mse c 260 msec 256 msec 14 ip104.44.136.216.in-addr.arpa (216.136.44.104) [AS 4323] 404 msec 400 msec 3 80 msec -Hank