Robtex

Up: 113.21.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 113.21.40.0/23
Down right: 113.21.42.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
113.21.40.0	PTR	0.40.21.113.isphone.com.au
113.21.40.0	A	cityofsydney.nsw.gov.au
113.21.40.95	A	mail.cityofsydney.nsw.gov.au
113.21.40.200	A	mail.mycoinsnow.com
113.21.40.200	A	cameronmckean.com
113.21.40.200	A	mrcrowdfunder.com
113.21.41.85	PTR	85.41.21.113.isphone.com.au
113.21.41.85	A	mail.pespk.com.au
113.21.41.192	PTR	113-21-41-192.au.viaip.com
113.21.41.192	A	mail.outdoorfabrications.com.au
113.21.41.192	A	autodiscover.outdoorfabrications.com.au
113.21.41.252	PTR	113-21-41-252.au.viaip.com
113.21.41.252	A	mail.candasurveyors.com.au
113.21.42.2	PTR	113-21-42-2.au.viaip.com
113.21.42.10	PTR	113-21-42-10.au.viaip.com
113.21.42.18	PTR	113-21-42-18.au.viaip.com
113.21.42.21	PTR	113-21-42-21.au.viaip.com
113.21.42.31	PTR	113-21-42-31.au.viaip.com
113.21.42.34	PTR	113-21-42-34.au.viaip.com
113.21.42.35	PTR	113-21-42-35.au.viaip.com
113.21.42.37	PTR	113-21-42-37.au.viaip.com
113.21.42.39	PTR	113-21-42-39.au.viaip.com
113.21.42.40	PTR	113-21-42-40.au.viaip.com
113.21.42.44	PTR	113-21-42-44.au.viaip.com
113.21.42.46	PTR	113-21-42-46.au.viaip.com
113.21.42.47	PTR	113-21-42-47.au.viaip.com
113.21.42.51	PTR	113-21-42-51.au.viaip.com
113.21.42.57	PTR	113-21-42-57.au.viaip.com
113.21.42.60	PTR	113-21-42-60.au.viaip.com
113.21.42.63	PTR	113-21-42-63.au.viaip.com
113.21.42.69	PTR	113-21-42-69.au.viaip.com
113.21.42.71	PTR	113-21-42-71.au.viaip.com
113.21.42.74	PTR	113-21-42-74.au.viaip.com
113.21.42.75	PTR	113-21-42-75.au.viaip.com
113.21.42.84	PTR	113-21-42-84.au.viaip.com
113.21.42.87	PTR	113-21-42-87.au.viaip.com
113.21.42.88	PTR	113-21-42-88.au.viaip.com
113.21.42.94	PTR	113-21-42-94.au.viaip.com
113.21.42.98	PTR	113-21-42-98.au.viaip.com
113.21.42.100	PTR	113-21-42-100.au.viaip.com
113.21.42.105	PTR	113-21-42-105.au.viaip.com
113.21.42.107	PTR	113-21-42-107.au.viaip.com
113.21.42.109	PTR	113-21-42-109.au.viaip.com
113.21.42.117	PTR	113-21-42-117.au.viaip.com
113.21.42.120	PTR	113-21-42-120.au.viaip.com
113.21.42.125	PTR	113-21-42-125.au.viaip.com
113.21.42.127	PTR	113-21-42-127.au.viaip.com
113.21.42.133	PTR	113-21-42-133.au.viaip.com
113.21.42.134	PTR	113-21-42-134.au.viaip.com
113.21.42.136	PTR	113-21-42-136.au.viaip.com
113.21.42.138	PTR	113-21-42-138.au.viaip.com
113.21.42.141	PTR	113-21-42-141.au.viaip.com
113.21.42.145	PTR	113-21-42-145.au.viaip.com
113.21.42.146	PTR	113-21-42-146.au.viaip.com
113.21.42.155	PTR	113-21-42-155.au.viaip.com
113.21.42.158	PTR	113-21-42-158.au.viaip.com
113.21.42.167	PTR	167.42.21.113.isphone.com.au
113.21.42.172	PTR	113-21-42-172.au.viaip.com
113.21.42.174	PTR	113-21-42-174.au.viaip.com
113.21.42.181	PTR	113-21-42-181.au.viaip.com
113.21.42.185	A	smartsalary.com
113.21.42.188	PTR	113-21-42-188.au.viaip.com
113.21.42.192	PTR	113-21-42-192.au.viaip.com
113.21.42.202	PTR	113-21-42-202.au.viaip.com
113.21.42.203	PTR	113-21-42-203.au.viaip.com
113.21.42.205	PTR	113-21-42-205.au.viaip.com
113.21.42.217	PTR	113-21-42-217.au.viaip.com
113.21.42.222	PTR	113-21-42-222.au.viaip.com
113.21.42.225	PTR	113-21-42-225.au.viaip.com
113.21.42.227	PTR	113-21-42-227.au.viaip.com
113.21.42.230	PTR	230.42.21.113.isphone.com.au
113.21.42.234	PTR	113-21-42-234.au.viaip.com
113.21.42.235	PTR	113-21-42-235.au.viaip.com
113.21.42.245	PTR	113-21-42-245.au.viaip.com
113.21.42.247	PTR	247.42.21.113.isphone.com.au
113.21.42.252	PTR	113-21-42-252.au.viaip.com