Robtex

Up: 204.74.100.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 204.74.101.0/25
Down right: 204.74.101.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
204.74.101.1	PTR	udns2.ultradns.net
204.74.101.1	A	udns2.ultradns.com
204.74.101.1	A	ns2.sunrox.com
204.74.101.243	PTR	ns2.staff-fma.com
204.74.101.244	PTR	ns2.bancinternetgroup.com
204.74.101.245	PTR	ns6.dns.net.nz
204.74.101.246	PTR	ns1.scholastic.com
204.74.101.246	A	ns2.scholastic.com
204.74.101.247	PTR	ns1.dns30.com
204.74.101.249	PTR	ns2.advent.com
204.74.101.251	A+PTR	nans2.levi.com
204.74.101.252	PTR	ns2.nsidns.net
204.74.101.253	PTR	udns2.newdotnet.net