Robtex

Up: 81.28.0.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 81.28.16.0/21
Down right: 81.28.24.0/21

IP	Type	Hostname
81.28.18.2	PTR	gate-16.pb.cz
81.28.18.5	PTR	gate-16.pb.cz
81.28.18.9	PTR	gate-16.pb.cz
81.28.18.17	PTR	gate-16.pb.cz
81.28.18.37	PTR	gate-16.pb.cz
81.28.18.49	PTR	gate-16.pb.cz
81.28.18.53	PTR	enge.nohelgarden.cz
81.28.18.57	PTR	gate-16.pb.cz
81.28.18.125	PTR	mail.ligmet.cz
81.28.18.129	PTR	gate-pentagon.pb.cz
81.28.18.193	PTR	gate-pentagon.pb.cz
81.28.18.209	PTR	gate-pentagon.pb.cz
81.28.18.241	PTR	gate-mu-dobris.pb.cz