Robtex

Up: 221.133.20.0/22
Can't show all results, try to descend to a more specific CIDR
Down left: 221.133.22.0/24
Down right: 221.133.23.0/24
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
221.133.22.8	PTR	mail2208.superdatavn.com
221.133.22.8	A	mail2208.maychuemail.com
221.133.22.19	PTR	mail2219.superdatavn.com
221.133.22.19	A	mail2219.maychuemail.com
221.133.22.34	PTR	mail2234.superdatavn.com
221.133.22.34	A	mail2234.maychuemail.com
221.133.22.69	PTR	mail2269.superdatavn.com
221.133.22.69	A	mail.navetco.com.vn
221.133.22.71	PTR	mail2271.superdatavn.com
221.133.22.71	A	mail.danavacation.com
221.133.22.73	A	mail.rareginvn.com
221.133.22.75	PTR	mail2275.superdatavn.com
221.133.22.75	A	mail2275.maychuemail.com
221.133.22.76	PTR	mail2276.superdatavn.com
221.133.22.76	A	mail.viphavet.com
221.133.22.81	PTR	mail2281.superdatavn.com
221.133.22.84	PTR	mail2284.superdatavn.com
221.133.22.84	A	mail.hunglongbranding.com
221.133.22.88	A+PTR	mail2288.superdatavn.com
221.133.22.88	A	mail.phuongnambook.com.vn
221.133.22.89	PTR	mail2289.superdatavn.com
221.133.22.92	PTR	mail2292.superdatavn.com
221.133.22.92	A	mail.lj-asia.com
221.133.22.94	PTR	mail2294.superdatavn.com
221.133.22.95	PTR	mail2295.superdatavn.com
221.133.22.95	A	mail.vitalconnections.com.vn
221.133.22.99	PTR	mail2299.superdatavn.com
221.133.22.99	A	mail.hoanggiangexim.com
221.133.22.101	PTR	mail22101.superdatavn.com
221.133.22.101	A	mail22101.maychuemail.com
221.133.22.102	PTR	mail22102.superdatavn.com
221.133.22.104	PTR	mail22104.superdatavn.com
221.133.22.104	A	mail.unsw.edu.vn
221.133.22.120	A	mail.vinalab.org.vn
221.133.22.121	PTR	mail22121.superdatavn.com
221.133.22.121	A	mail.ms-cap.com
221.133.22.126	PTR	mail22126.superdatavn.com
221.133.22.126	A	we41logistics.com
221.133.22.137	PTR	mail22137.superdatavn.com
221.133.22.137	A	mail.hnh.com.vn
221.133.22.137	A	mail.vietnamflowerscorp.com
221.133.22.139	PTR	mail22139.superdatavn.com
221.133.22.139	A	mx.mhe.vn
221.133.22.142	PTR	mail22142.superdatavn.com
221.133.22.142	A	mail.asiadragon.com.vn
221.133.22.145	PTR	mail22145.superdatavn.com
221.133.22.145	A	mail.diamondcutter.productions
221.133.22.148	PTR	mail22148.superdatavn.com
221.133.22.148	A	mail.telelink.vn
221.133.22.148	A	mail.haihan.vn
221.133.22.156	A	apparelgroup.com.vn
221.133.22.157	PTR	mail22157.superdatavn.com
221.133.22.157	A	mail.baconco.com.vn
221.133.22.158	PTR	mail22158.superdatavn.com
221.133.22.158	A	mail.mat-vn.com
221.133.22.159	PTR	mail22159.superdatavn.com
221.133.22.162	PTR	mail22162.superdatavn.com
221.133.22.164	PTR	mail22164.superdatavn.com
221.133.22.164	A	mail22164.maychuemail.com
221.133.22.176	A+PTR	mail22176.superdatavn.com
221.133.22.178	A+PTR	mail22178.superdatavn.com
221.133.22.178	A	mail22178.maychuemail.com
221.133.22.179	PTR	mail22179.superdatavn.com
221.133.22.179	A	mail22179.maychuemail.com
221.133.22.183	A+PTR	mail22183.superdatavn.com
221.133.22.183	A	mail.dinhthien.com.vn
221.133.22.183	A	mail.quangphuctech.com.vn