Robtex

Up: 216.166.104.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 216.166.104.0/23
Down right: 216.166.106.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
216.166.105.131	PTR	news.giganews.com
216.166.105.139	PTR	ns4.giganews.com
216.166.105.139	A+PTR	ns1.ams1.giganews.com
216.166.105.139	A	ns1.ams.giganews.com
216.166.105.140	PTR	text.giganews.com
216.166.105.144	A+PTR	news-europe.giganews.com
216.166.105.145	PTR	europe.isp.giganews.com
216.166.105.145	A	news.xenosite.net
216.166.105.145	A	news.btinternet.com
216.166.105.161	PTR	news.powerusenet.com
216.166.105.171	A+PTR	216-166-105-171.fwd.datafoundry.com
216.166.106.31	A+PTR	serv2.ams1.giganews.com
216.166.106.74	PTR	216-166-106-74.fwd.datafoundry.com
216.166.106.74	A	news-out.nntp.giganews.com
216.166.106.75	PTR	216-166-106-75.fwd.datafoundry.com
216.166.106.75	A	news-out.nntp.giganews.com
216.166.106.76	PTR	216-166-106-76.fwd.datafoundry.com
216.166.106.76	A	news-out.nntp.giganews.com
216.166.106.77	PTR	216-166-106-77.fwd.datafoundry.com
216.166.106.77	A	news-out.nntp.giganews.com
216.166.106.84	PTR	216-166-106-84.fwd.datafoundry.com
216.166.106.84	A	news-out.nntp.giganews.com
216.166.106.85	PTR	216-166-106-85.fwd.datafoundry.com
216.166.106.85	A	news-out.nntp.giganews.com
216.166.106.90	PTR	216-166-106-90.fwd.datafoundry.com
216.166.106.90	A	news-out.nntp.giganews.com
216.166.106.91	PTR	216-166-106-91.fwd.datafoundry.com
216.166.106.91	A	news-out.nntp.giganews.com
216.166.106.92	PTR	216-166-106-92.fwd.datafoundry.com
216.166.106.92	A	news-out.nntp.giganews.com
216.166.106.93	PTR	216-166-106-93.fwd.datafoundry.com
216.166.106.93	A	news-out.nntp.giganews.com
216.166.106.94	PTR	backlog3.nntp.ams1.giganews.com
216.166.106.94	A	news-out.nntp.giganews.com
216.166.106.95	PTR	backlog4.nntp.ams1.giganews.com
216.166.106.95	A	news-out.nntp.giganews.com
216.166.106.141	A+PTR	cs12-1.ams1.giganews.com
216.166.106.161	PTR	216-166-106-161.fwd.datafoundry.com