Robtex

Up: 5.57.20.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 5.57.20.0/25
Down right: 5.57.20.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
5.57.20.8	A	proxy-gw-l.booking.com
5.57.20.11	A	vpn2.booking.com
5.57.20.11	A	vpn.booking.com
5.57.20.24	A	gw1gp1.booking.com
5.57.20.25	A	gw1gp2.booking.com
5.57.20.26	A	gw1gp3.booking.com
5.57.20.29	A	gw2gp5.booking.com
5.57.20.36	A+PTR	webconf.booking.com
5.57.20.72	A	outlook.booking.com
5.57.20.80	A	mgp.booking.com
5.57.20.128	A	google.itspublic.booking.com
5.57.20.128	A	federate.itspublic.booking.com
5.57.20.128	A	google.booking.com
5.57.20.129	A	proxy-out-l.booking.com
5.57.20.136	A+PTR	mercury-mp201.booking.com
5.57.20.136	A	mercury.booking.com
5.57.20.142	PTR	xmpp-l2.booking.com
5.57.20.142	A	apidev.itspublic.booking.com
5.57.20.143	A	webtop.itspublic.booking.com
5.57.20.145	A	crx.internal.itspublic.booking.com
5.57.20.147	A	idp.itspublic.booking.com
5.57.20.147	A	youat.booking.com
5.57.20.147	A	globalgurusso.booking.com
5.57.20.151	A	jira.itspublic.booking.com
5.57.20.153	A	api.voice.itspublic.booking.com
5.57.20.160	A+PTR	prodout-l.booking.com
5.57.20.166	A+PTR	mail-lhr4-214.booking.com
5.57.20.166	A	mercury.booking.com
5.57.20.166	A	ns0.activehotels.net
5.57.20.167	A+PTR	mail-lhr4-213.booking.com
5.57.20.167	A	mercury.booking.com
5.57.20.167	A	ns1.activehotels.net
5.57.20.176	A+PTR	mail-me5.booking.com
5.57.20.177	A+PTR	mail-me6.booking.com
5.57.20.177	A	engine.booking.com
5.57.20.177	A	mailer.booking.com
5.57.20.178	A+PTR	mx201.booking.com
5.57.20.178	A	mx5.booking.com
5.57.20.179	A+PTR	mx202.booking.com
5.57.20.179	A	mx6.booking.com
5.57.20.182	A+PTR	mail-out5.booking.com
5.57.20.186	A+PTR	sg-l-mail-9.booking.com
5.57.20.188	A+PTR	sg-l-mail-11.booking.com
5.57.20.190	A+PTR	mail-me7.booking.com
5.57.20.190	A	engine.booking.com
5.57.20.190	A	mailer.booking.com
5.57.20.192	A+PTR	mail-rv5.booking.com
5.57.20.192	A	engine.booking.com
5.57.20.192	A	mailer.booking.com
5.57.20.193	A+PTR	mail-rv6.booking.com
5.57.20.194	A	mail-rv7.booking.com
5.57.20.195	A+PTR	mx210.booking.com
5.57.20.201	A+PTR	mx211.booking.com
5.57.20.201	A	mx3.booking.com
5.57.20.204	A+PTR	mercury-mp202.booking.com
5.57.20.204	A	mercury.booking.com
5.57.20.207	A	mx212.booking.com