Robtex

Up: 137.221.200.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 137.221.200.0/23
Down right: 137.221.202.0/23

IP	Type	Hostname
137.221.201.9	A+PTR	smtp2.telent.com
137.221.201.9	A	smtp.telent.com
137.221.201.11	A+PTR	smtp1.telent.com
137.221.201.11	A	smtp.telent.com
137.221.201.174	PTR	host-174.telent-labs.org.uk
137.221.201.174	A	fw1.telent-labs.org.uk
137.221.201.176	A+PTR	mail.telent-labs.org.uk
137.221.201.177	A+PTR	ns0.telent-labs.org.uk
137.221.201.177	A	wk-lab-dns1.telent-labs.org.uk
137.221.201.178	A+PTR	ns1.telent-labs.org.uk
137.221.201.180	PTR	host-180.telent-labs.org.uk
137.221.201.180	A	telent-labs.org.uk