Robtex

Up: 123.255.200.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 123.255.200.0/23
Down right: 123.255.202.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
123.255.200.1	PTR	ip-123-255-200-1.datautama.net.id
123.255.200.1	A	spjt.co.id
123.255.200.4	PTR	ip-123.255.200-4.datautama.net.id
123.255.200.25	PTR	ip-123-255-200-25.datautama.net.id
123.255.200.25	A	dminputoperations.web.id
123.255.200.25	A	www.dminputoperations.web.id
123.255.200.61	PTR	ip-123-255-200-61.datautama.net.id
123.255.200.61	A	mail.sumbiri.com
123.255.200.98	PTR	ip-123-255-200-98.datautama.net.id
123.255.200.158	PTR	ip-123-255-200-158.datautama.net.id
123.255.200.222	PTR	ip-123-255-200-222.datautama.net.id
123.255.200.222	A	www.premmiere.co.id
123.255.201.1	A	ns1.7vcloud.com
123.255.201.1	A	ns2.7vcloud.com
123.255.201.26	PTR	smtpku.ptmorich.com
123.255.201.27	A+PTR	mta.ptmorich.com
123.255.201.30	A	smtpku.ptmorich.com
123.255.201.33	PTR	ip-123-255-201-33.datautama.net.id
123.255.201.54	PTR	ip-123-255-201-54.datautama.net.id
123.255.201.81	PTR	ip-123-255-201-81.datautama.net.id
123.255.201.122	PTR	ip-123-255-201-122.datautama.net.id
123.255.201.126	PTR	ip-123-255-201-126.datautama.net.id
123.255.201.142	PTR	ip-123-255-201-142.datautama.net.id
123.255.201.154	PTR	ip-123-255-201-154.datautama.net.id
123.255.201.162	PTR	ip-123-255-201-162.datautama.net.id
123.255.201.163	PTR	ip-123-255-201-163.datautama.net.id
123.255.201.174	PTR	ip-123-255-201-174.datautama.net.id
123.255.201.174	A	digilib.ekonomiuntagsmg.ac.id
123.255.201.174	A	ekonomiuntagsmg.ac.id
123.255.201.177	A	gw.ast.co.id
123.255.201.186	PTR	ip-123-255-201-186.datautama.net.id
123.255.201.186	A	mail.ast.co.id
123.255.201.202	PTR	ip-123-255-201-202.datautama.net.id
123.255.201.254	A	mail.hinocemaco.co.id
123.255.202.7	PTR	ip-123-255-202-7.datautama.net.id
123.255.202.18	PTR	ip-123-255-202-18.datautama.net.id
123.255.202.19	A+PTR	ns4.datautama.net.id
123.255.202.20	PTR	ip-123-255-202-20.datautama.net.id
123.255.202.20	A	speedtest.sby.datautama.net.id
123.255.202.21	A+PTR	lg.datautama.net.id
123.255.202.22	PTR	ip-123-255-202-22.datautama.net.id
123.255.202.22	A	nurdin.web.id
123.255.202.38	PTR	ip-123-255-202-38.datautama.net.id
123.255.202.50	A	mail.rumah-teknologi.net
123.255.202.50	A	mail.kpsi-bsd.com
123.255.202.52	PTR	ip-123-255-202-52.datautama.net.id
123.255.202.60	A	musabaqah.id
123.255.202.74	A+PTR	kartolo.sby.datautama.net.id
123.255.202.82	PTR	mail.sdm4sby.sch.id
123.255.202.83	A	mail.sdm4sby.sch.id
123.255.202.84	A	sdm4sby.sch.id
123.255.202.84	A	sdm4sby.net
123.255.202.90	PTR	ip-123-255-202-90.datautama.net.id
123.255.202.218	A	pt-imp.com
123.255.202.243	PTR	ip-123-255-202-243.datautama.net.id
123.255.202.243	A	ptlumipack.com
123.255.202.245	PTR	ip-123-255-202-245.datautama.net.id
123.255.202.245	A	mpas.co.id
123.255.203.10	PTR	ip-123-255-203-10.datautama.net.id
123.255.203.17	PTR	ip-123-255-203-17.datautama.net.id
123.255.203.17	A	mail.kingdomindah.com
123.255.203.18	PTR	ip-123-255-203-18.datautama.net.id
123.255.203.18	A	mail.kingdomindah.com
123.255.203.18	A	mail.taihokingdom.com
123.255.203.35	PTR	ip-123-255-203-35.datautama.net.id
123.255.203.42	PTR	ip-123-255-203-42.datautama.net.id
123.255.203.66	PTR	ip-123-255-203-66.datautama.net.id
123.255.203.66	A	mailserver.gunawangsahotel.com
123.255.203.178	PTR	ip-123-255-203-178.datautama.net.id
123.255.203.189	PTR	ip-123-255-203-189.datautama.net.id
123.255.203.235	A	sipatensidoarjo.com
123.255.203.236	PTR	ip-123-255-203-236.datautama.net.id