Robtex

Up: 203.172.120.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 203.172.120.0/23
Down right: 203.172.122.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
203.172.120.34	A+PTR	mailgateway.centaco.com
203.172.120.35	A+PTR	mail.centaco.com
203.172.120.51	PTR	mail.umwsiam.com
203.172.120.51	A	webmail.umwsiam.com
203.172.121.55	PTR	mail.ert.co.th
203.172.121.55	A	ert.co.th
203.172.121.55	A	www.ert.co.th
203.172.121.56	A+PTR	mail.ert.co.th
203.172.121.56	A	info.ert.co.th
203.172.121.56	A	mail2.ert.co.th
203.172.121.57	A	ertla.com
203.172.121.84	A+PTR	br-mail.breuning.co.th
203.172.121.84	A	www.breuning.co.th
203.172.121.84	A	tracking.breuning.co.th
203.172.121.124	A	landsteadonline.com
203.172.121.130	A+PTR	mail.cbstour.co.th
203.172.121.131	A+PTR	pop3.cbstour.co.th
203.172.121.132	A+PTR	mail.discoveryaviation.co.th
203.172.121.134	A	mail.bugary.com
203.172.121.134	A	pop3.cbstour.com
203.172.121.134	A	bugary.com
203.172.121.137	A	ns1.cbstravelasia.com
203.172.121.137	A	ns2.cbstravelasia.com
203.172.121.138	A	aluxtrip.com
203.172.121.138	A	mail.aluxtrip.com
203.172.121.138	A	www.cbstour.com
203.172.121.140	A	ns2.cbstour.com
203.172.121.140	A	ns1.cbstour.com
203.172.121.140	A	www.cbstour.com
203.172.121.141	PTR	mail.cbstechnology.co.th
203.172.121.141	A	mail.bugary.com
203.172.121.150	A+PTR	webmail.kiriuthailand.com
203.172.121.150	A	kthsv1.kiriuthailand.com
203.172.121.150	A	kiriuthailand.com
203.172.121.162	A+PTR	matgw.mat.co.th
203.172.121.162	A	mat-gw.mat.co.th
203.172.121.165	A+PTR	matgw.mat.co.th
203.172.121.181	PTR	garoon.mat.co.th
203.172.121.182	PTR	scan.mat.co.th
203.172.121.184	A+PTR	relay.mat.co.th
203.172.121.185	A+PTR	mail.b-en-g.co.th
203.172.121.185	A+PTR	ns.b-en-g.co.th
203.172.123.199	A	webmail.siphhospital.com
203.172.123.199	A	email.siphhospital.com
203.172.123.199	A	webmail.siph.siphhospital.com
203.172.123.201	A+PTR	mail1.siphhospital.com
203.172.123.202	A+PTR	mail1.siphhospital.com
203.172.123.203	A+PTR	mail2.siphhospital.com
203.172.123.204	A+PTR	mail2.siphhospital.com