Robtex

Up: 172.217.192.0/18
Can't show all results, try to descend to a more specific CIDR
Down left: 172.217.224.0/20
Down right: 172.217.240.0/20

IP	Type	Hostname
172.217.235.0	PTR	0.235.217.172.bc.googleusercontent.com
172.217.235.10	PTR	10.235.217.172.bc.googleusercontent.com
172.217.235.125	PTR	125.235.217.172.bc.googleusercontent.com
172.217.240.0	A+PTR	0.240.217.172.bc.googleusercontent.com
172.217.253.61	A+PTR	61.253.217.172.bc.googleusercontent.com
172.217.255.255	A+PTR	255.255.217.172.bc.googleusercontent.com