Robtex

Up: 221.133.0.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 221.133.0.0/23
Down right: 221.133.2.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
221.133.0.1	A+PTR	hcmc.saigonnet.vn
221.133.0.2	PTR	hcmc1.saigonnet.vn
221.133.0.2	A	misubo459.com
221.133.0.2	A	sergiotacchini.com.vn
221.133.0.4	A	noc.ipt.vn
221.133.0.5	PTR	dnssec.saigonnet.vn
221.133.0.162	A	iboxplus.vn
221.133.0.163	A	www.iboxplus.com
221.133.0.163	A	mail.iboxplus.com
221.133.0.204	A	r1---sn-n2u-nbos.googlevideo.com
221.133.0.204	A	r1.sn-n2u-nbos.gvt1.com
221.133.0.204	A	r1.sn-n2u-nbos.googlevideo.com
221.133.1.1	A+PTR	hcmc2.saigonnet.vn
221.133.1.2	PTR	hcmc3.saigonnet.vn
221.133.1.3	PTR	hcmc5.saigonnet.vn
221.133.1.4	PTR	mail.store2.spt.vn
221.133.1.4	A	mail.tramdungnghibinhan.vn
221.133.1.4	A	mail.store.spt.vn
221.133.1.6	PTR	mail.store3.spt.vn
221.133.1.12	PTR	store.spt.vn
221.133.1.17	PTR	wmail.saigonnet.vn
221.133.1.18	PTR	mail.cyvee.com
221.133.1.18	PTR	mail.cyveemail.com
221.133.1.18	PTR	mail.bross.vn
221.133.1.24	PTR	mail.spt.vn
221.133.1.37	PTR	mail.web37.ipt.vn
221.133.1.37	A	mail.datrifood.com
221.133.1.37	A	sgtelecom.vn
221.133.1.40	A	nhavesinhsachkhuan.com
221.133.1.40	A	briteimpressionsdental.com
221.133.1.41	PTR	mail.saigonnews.vn
221.133.1.41	A	mail.saigonnews.com.vn
221.133.1.41	A	suasacdep.com
221.133.1.42	PTR	mail.web1.ipt.vn
221.133.1.44	PTR	mail.saigonpostel.com.vn
221.133.1.45	PTR	mail.ipt.vn
221.133.1.46	PTR	gwserv1.spt.vn
221.133.1.47	PTR	mail.web47.ipt.vn
221.133.1.47	A	dongsongnho.com
221.133.1.47	A	cuoihoi24h.com
221.133.1.49	A+PTR	web49.ipt.vn
221.133.1.49	A	mail.phuquochotel.net
221.133.1.49	A	casinophuquoc.net
221.133.1.50	PTR	mail.bachvietdt.vn
221.133.1.50	PTR	mail.bachvietdt.com.vn
221.133.1.50	PTR	mail.bvmedia.com.vn
221.133.1.52	PTR	mail.mesa.vn
221.133.1.52	PTR	mailserver.mesa.com.vn
221.133.1.52	PTR	mail.mld.mesa.vn
221.133.1.56	A+PTR	mail.store1.spt.vn
221.133.1.56	A	mail.dangkytenmien.vn
221.133.1.57	A	sptfone.com.vn
221.133.1.57	A	stc.spt.vn
221.133.1.59	PTR	mail2.mx.dangkytenmien.vn
221.133.1.59	A	mail.store1.spt.vn
221.133.1.60	PTR	mail.spt.vn
221.133.1.60	A	mail.saigonpostel.com.vn
221.133.1.75	A+PTR	mail.web75.ipt.vn
221.133.1.75	A	web75.ipt.vn
221.133.1.77	A	snetfone.com.vn
221.133.1.88	PTR	mail.web88.ipt.vn
221.133.1.88	A	inetns1.thuemaytinh.com.vn
221.133.1.88	A	galleries.thuemaytinh.com.vn
221.133.1.136	A+PTR	mail1.noc.ipt.vn
221.133.1.142	PTR	demo.saigonnet.vn
221.133.1.167	PTR	mail.test.saigonnet.vn
221.133.1.176	A+PTR	mail.noc.ipt.vn
221.133.3.2	PTR	exchange.fairfield.com.vn
221.133.3.11	A	lbmnice.com
221.133.3.18	A	mail.vn.fostersgroup.com
221.133.3.27	A	minhtruong.net
221.133.3.37	PTR	mail.fvhospital.com
221.133.3.44	A	libra-vn.com
221.133.3.50	PTR	mail.pmh.com.vn
221.133.3.50	A	mail1.pmh.com.vn
221.133.3.69	A+PTR	mail.callcenter.ipt.vn
221.133.3.82	PTR	smtp.spt.com.vn
221.133.3.83	PTR	mta.spt.vn
221.133.3.83	A	mail.spt.vn
221.133.3.83	A	smtp.spt.vn
221.133.3.98	PTR	mailserver.photron.com.vn
221.133.3.111	PTR	mailserver.sofitelsaigon.com.vn
221.133.3.114	PTR	mail.motivesfareast.com
221.133.3.114	A	motivesvietnam.com
221.133.3.114	A	motivessoft.com
221.133.3.129	PTR	mail.shingmark.com.vn
221.133.3.129	A	mail.shingmarkhospital.com
221.133.3.130	A	www.shingmark.com.vn
221.133.3.130	A	shingmark.com.vn
221.133.3.142	A	mail.shingmark.com.vn
221.133.3.162	PTR	mail.hoamattroi.com
221.133.3.163	PTR	mail.hoamattroi.com
221.133.3.163	A	mail.geumsan.com.vn
221.133.3.165	A	mail.petechim.com.vn
221.133.3.166	PTR	petechim.com.vn
221.133.3.166	A	pte-edge-01.petechim.com.vn
221.133.3.166	A	edge.petechim.vn
221.133.3.182	A+PTR	mx1.halgroup.com.vn
221.133.3.194	A	mail.sgvf.vn
221.133.3.196	PTR	mail.sgvf.com.vn
221.133.3.210	A	mail.lamdepgiare.com
221.133.3.231	PTR	server.somotweb1.com