Robtex

Up: 2600:1801:13::/48
Can't show all results, try to descend to a more specific CIDR
Down left: 2600:1801:13::/50
Down right: 2600:1801:13:4000::/50
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
2600:1801:13::1	PTR	ns13.dnsmadeeasy.com
2600:1801:13::1	A	ns4.cdsinchosting.com
2600:1801:13::1	A	ns3.flrvinspections.com
2600:1801:13::17	PTR	ns13.markleycloud.com
2600:1801:13::1:16	PTR	ns8.dns-netix.net