Robtex

Up: 31.130.224.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 31.130.228.0/23
Down right: 31.130.230.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
31.130.229.6	A+PTR	smtp.meeting.ietf.org
31.130.229.6	A	ns1.meeting.ietf.org
31.130.229.6	A	ntp.meeting.ietf.org
31.130.229.7	PTR	ns2.meeting.ietf.org
31.130.229.7	A	ntp.meeting.ietf.org
31.130.229.12	A	meeting.ietf.org