Robtex

Up: 103.55.58.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 103.55.59.0/25
Down right: 103.55.59.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
103.55.59.32	A+PTR	mail1.sso.go.th
103.55.59.33	A+PTR	mail2.sso.go.th
103.55.59.34	A+PTR	ns01.sso.go.th
103.55.59.38	A+PTR	www.sso.go.th
103.55.59.39	A+PTR	cus.sso.go.th
103.55.59.40	A+PTR	web.sso.go.th
103.55.59.43	A+PTR	ftp.sso.go.th
103.55.59.44	PTR	lib.sso.go.th
103.55.59.45	A+PTR	irc.sso.go.th
103.55.59.46	A+PTR	mail.sso.go.th
103.55.59.47	A+PTR	pop.sso.go.th
103.55.59.47	A+PTR	smtp.sso.go.th
103.55.59.47	A+PTR	webmail.sso.go.th
103.55.59.48	A+PTR	eservice.sso.go.th
103.55.59.49	A+PTR	sftp.sso.go.th
103.55.59.49	A+PTR	arts.sso.go.th
103.55.59.50	A+PTR	ue.sso.go.th
103.55.59.90	A	wa1.sso.go.th
103.55.59.186	A+PTR	apigw.sso.go.th