Robtex

Up: 158.72.128.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 158.72.128.0/21
Down right: 158.72.136.0/21

IP	Type	Hostname
158.72.139.19	A+PTR	smtp.ees.hhs.gov
158.72.139.19	A	smtp.hhs.gov
158.72.139.20	PTR	owa.hhs.gov
158.72.139.22	PTR	webmail.hhs.gov
158.72.139.23	A	autodiscover.hhs.gov
158.72.139.58	A+PTR	smtp01.ees.hhs.gov
158.72.139.59	A+PTR	smtp02.ees.hhs.gov