Robtex

Up: 54.240.56.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 54.240.56.0/23
Down right: 54.240.58.0/23

IP	Type	Hostname
54.240.56.1	A+PTR	a56-1.smtp-out.eu-west-1.amazonses.com
54.240.56.20	A+PTR	a56-20.smtp-out.eu-west-1.amazonses.com
54.240.56.21	A	a56-21.smtp-out.eu-west-1.amazonses.com
54.240.56.73	A	a56-73.smtp-out.eu-west-1.amazonses.com
54.240.56.74	A+PTR	a56-74.smtp-out.eu-west-1.amazonses.com
54.240.56.75	A	a56-75.smtp-out.eu-west-1.amazonses.com
54.240.56.82	PTR	a56-82.smtp-out.eu-west-1.amazonses.com
54.240.56.179	PTR	a56-179.smtp-out.eu-west-1.amazonses.com
54.240.57.4	A+PTR	a57-4.smtp-out.us-west-2.amazonses.com
54.240.57.5	A+PTR	a57-5.smtp-out.us-west-2.amazonses.com
54.240.57.11	A	a57-11.smtp-out.us-west-2.amazonses.com
54.240.57.12	A	a57-12.smtp-out.us-west-2.amazonses.com
54.240.57.29	A	a57-29.smtp-out.us-west-2.amazonses.com
54.240.57.30	A+PTR	a57-30.smtp-out.us-west-2.amazonses.com
54.240.57.39	A+PTR	a57-39.smtp-out.us-west-2.amazonses.com
54.240.57.46	A+PTR	a57-46.smtp-out.us-west-2.amazonses.com
54.240.57.47	A+PTR	a57-47.smtp-out.us-west-2.amazonses.com
54.240.57.55	A	a57-55.smtp-out.us-west-2.amazonses.com
54.240.57.59	A	a57-59.smtp-out.us-west-2.amazonses.com
54.240.57.60	A	a57-60.smtp-out.us-west-2.amazonses.com
54.240.57.61	A+PTR	a57-61.smtp-out.us-west-2.amazonses.com
54.240.57.83	A+PTR	a57-83.smtp-out.us-west-2.amazonses.com
54.240.57.84	A+PTR	a57-84.smtp-out.us-west-2.amazonses.com
54.240.57.85	A+PTR	a57-85.smtp-out.us-west-2.amazonses.com
54.240.57.99	A+PTR	a57-99.smtp-out.us-west-2.amazonses.com
54.240.57.131	A	a57-131.smtp-out.us-west-2.amazonses.com
54.240.57.164	A+PTR	a57-164.smtp-out.us-west-2.amazonses.com
54.240.57.220	A+PTR	a57-220.smtp-out.us-west-2.amazonses.com
54.240.57.227	A+PTR	a57-227.smtp-out.us-west-2.amazonses.com
54.240.58.11	A+PTR	a58-11.smtp-out.us-west-2.amazonses.com
54.240.58.21	A+PTR	a58-21.smtp-out.us-west-2.amazonses.com
54.240.58.22	A+PTR	a58-22.smtp-out.us-west-2.amazonses.com
54.240.58.23	A+PTR	a58-23.smtp-out.us-west-2.amazonses.com
54.240.58.46	A+PTR	a58-46.smtp-out.us-west-2.amazonses.com
54.240.58.47	A+PTR	a58-47.smtp-out.us-west-2.amazonses.com
54.240.58.56	A+PTR	a58-56.smtp-out.us-west-2.amazonses.com
54.240.58.58	A+PTR	a58-58.smtp-out.us-west-2.amazonses.com
54.240.58.59	A+PTR	a58-59.smtp-out.us-west-2.amazonses.com
54.240.58.60	A+PTR	a58-60.smtp-out.us-west-2.amazonses.com
54.240.58.61	A+PTR	a58-61.smtp-out.us-west-2.amazonses.com
54.240.58.62	A+PTR	a58-62.smtp-out.us-west-2.amazonses.com
54.240.58.64	A+PTR	a58-64.smtp-out.us-west-2.amazonses.com
54.240.58.65	A+PTR	a58-65.smtp-out.us-west-2.amazonses.com
54.240.58.80	A+PTR	a58-80.smtp-out.us-west-2.amazonses.com
54.240.58.81	A+PTR	a58-81.smtp-out.us-west-2.amazonses.com
54.240.58.82	A+PTR	a58-82.smtp-out.us-west-2.amazonses.com
54.240.58.126	A+PTR	a58-126.smtp-out.us-west-2.amazonses.com
54.240.58.127	A+PTR	a58-127.smtp-out.us-west-2.amazonses.com
54.240.58.160	A	a58-160.smtp-out.us-west-2.amazonses.com
54.240.58.199	PTR	a58-199.smtp-out.us-west-2.amazonses.com
54.240.59.50	A+PTR	a59-50.smtp-out.us-west-2.amazonses.com
54.240.59.63	A+PTR	a59-63.smtp-out.us-west-2.amazonses.com
54.240.59.252	A	a59-252.smtp-out.us-west-2.amazonses.com