Robtex

Up: 193.151.16.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 193.151.20.0/23
Down right: 193.151.22.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
193.151.20.1	PTR	ns2.securens.net
193.151.20.2	PTR	ns4.securens.net
193.151.20.57	PTR	mail.dilex.bg
193.151.23.2	A+PTR	ns2.netwlan.net
193.151.23.2	A	ns2.paralax.org
193.151.23.2	A	ns2.plashim.se
193.151.23.234	A	gps.paralax.org
193.151.23.234	A	mail.plashim.se
193.151.23.234	A	ns1.plashim.se