Robtex

Up: 87.101.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 87.101.40.0/23
Down right: 87.101.42.0/23

IP	Type	Hostname
87.101.40.2	PTR	gw.piekary.net
87.101.40.3	A+PTR	admin.piekary.net
87.101.40.5	PTR	piekary.net
87.101.40.5	A	mx.piekary.net
87.101.40.6	A	cache1.piekary.net
87.101.40.7	A	cache2.piekary.net
87.101.40.8	A	cache3.piekary.net
87.101.40.9	A+PTR	cache.piekary.net