Robtex

Up: 78.128.56.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 78.128.56.0/23
Down right: 78.128.58.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
78.128.56.6	PTR	ip-56-6.powernet.bg
78.128.56.7	PTR	ip-56-7.powernet.bg
78.128.56.9	PTR	ip-56-9.powernet.bg
78.128.56.28	PTR	ip-56-28.powernet.bg
78.128.56.53	PTR	ip-56-53.powernet.bg
78.128.56.56	PTR	ip-56-56.powernet.bg
78.128.56.70	PTR	ip-56-70.powernet.bg
78.128.56.84	A+PTR	78-128-56-84.slvn.ddns.bulsat.com
78.128.56.98	PTR	ip-56-98.powernet.bg
78.128.56.108	PTR	ip-56-108.powernet.bg
78.128.56.119	PTR	ip-56-119.powernet.bg
78.128.56.124	PTR	ip-56-124.powernet.bg
78.128.56.135	PTR	ip-56-135.powernet.bg
78.128.56.158	PTR	ip-56-158.powernet.bg
78.128.56.170	PTR	ip-56-170.powernet.bg
78.128.56.191	PTR	ip-56-191.powernet.bg
78.128.56.197	PTR	ip-56-197.powernet.bg
78.128.56.219	A+PTR	78-128-56-219.slvn.ddns.bulsat.com
78.128.56.229	PTR	ip-56-229.powernet.bg
78.128.56.235	PTR	ip-56-235.powernet.bg
78.128.56.240	PTR	ip-56-240.powernet.bg
78.128.56.241	PTR	ip-56-241.powernet.bg
78.128.56.250	PTR	ip-56-250.powernet.bg
78.128.57.93	PTR	ip-57-93.powernet.bg
78.128.57.129	PTR	ip-57-129.powernet.bg
78.128.57.229	PTR	ip-57-229.powernet.bg
78.128.57.233	PTR	ip-57-233.powernet.bg
78.128.58.1	PTR	ip-58-1.powernet.bg
78.128.58.7	A	mail2.insinfotrade.com
78.128.58.7	A	mail2.brokerins.bg
78.128.58.16	PTR	ip-58-16.powernet.bg
78.128.58.18	PTR	ip-58-18.powernet.bg
78.128.58.58	PTR	ip-58-58.powernet.bg
78.128.58.60	PTR	ip-58-60.powernet.bg
78.128.58.109	PTR	ip-58-109.powernet.bg
78.128.58.121	PTR	ip-58-121.powernet.bg
78.128.58.121	A	mx0.premyanov-lawfirm.com
78.128.58.121	A	mx.premyanov-lawfirm.com
78.128.59.1	PTR	ip-59-1.powernet.bg
78.128.59.2	PTR	ns27.rookdns.com
78.128.59.3	PTR	ip-59-3.powernet.bg
78.128.59.61	PTR	ip-59-61.powernet.bg
78.128.59.107	PTR	ip-59-107.powernet.bg
78.128.59.119	PTR	ip-59-119.powernet.bg
78.128.59.174	PTR	ip-59-174.powernet.bg
78.128.59.238	PTR	ip-59-238.powernet.bg