Robtex

Up: 81.21.34.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 81.21.34.0/25
Down right: 81.21.34.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
81.21.34.34	A+PTR	mail.callsat-telecom.com
81.21.34.34	A	mail.reserve3024.com
81.21.34.34	A	mail.callsat-telecom.net
81.21.34.35	A+PTR	ns1.callsat-telecom.com
81.21.34.36	A+PTR	ns2.callsat-telecom.com
81.21.34.38	PTR	mail2.callsat-telecom.com
81.21.34.40	A+PTR	mail2.callsat.com.cy
81.21.34.40	PTR	mail2.callsat-telecom.com
81.21.34.40	A	mail2.sievertlarssonscholarships.org
81.21.34.245	PTR	mail.callsat.net
81.21.34.250	A	mail.callsat.eu
81.21.34.253	A	fw.callsat-telecom.com