Robtex

Up: 204.138.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 204.138.40.0/23
Down right: 204.138.42.0/23

IP	Type	Hostname
204.138.40.34	A	webmail.lbugroup.com
204.138.40.36	A	mail.lbugroup.com
204.138.40.47	A	mail.mga-insurance.com
204.138.40.224	PTR	ll01.cc03-04.atl.teloip.net
204.138.40.226	PTR	ll03.cc03-04.atl.teloip.net
204.138.40.228	A+PTR	ll05.cc03-04.atl.teloip.net
204.138.40.229	PTR	ll06.cc03-04.atl.teloip.net
204.138.40.230	A+PTR	ll07.cc03-04.atl.teloip.net
204.138.40.231	A+PTR	ll08.cc03-04.atl.teloip.net
204.138.40.242	PTR	cc04.atl.teloip.net
204.138.40.243	PTR	cc03-04.atl.teloip.net
204.138.40.252	PTR	rs01-dmz.atl.teloip.net
204.138.40.253	PTR	rs02-dmz.atl.teloip.net
204.138.40.255	PTR	broadcast.atl.teloip.net.40.138.204.in-addr.arpa