Robtex

Up: 63.90.78.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 63.90.79.0/25
Down right: 63.90.79.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
63.90.79.5	PTR	gateway.massmutual.com
63.90.79.6	PTR	gateway.babsoncapital.com
63.90.79.7	A+PTR	mailexvip.massmutual.com
63.90.79.7	A	mail.massmutual.com
63.90.79.7	A	mobile.massmutual.com
63.90.79.9	A+PTR	mx_hold.massmutual.com
63.90.79.10	PTR	lyncweb.massmutual.com
63.90.79.11	PTR	lyncweb.babsoncapital.com
63.90.79.13	PTR	lyncweb.cornerstoneadvisers.com
63.90.79.16	A	gateway.cornerstoneadvisers.com
63.90.79.24	A+PTR	mmvsp.massmutual.com
63.90.79.25	A+PTR	misentryeas.massmutual.com
63.90.79.28	A	lync13-access.massmutual.com
63.90.79.31	A	lync13-access.massmutual.com
63.90.79.34	A+PTR	autodiscover.babsoncapital.com
63.90.79.34	A+PTR	autodiscover.financialguide.com
63.90.79.34	A+PTR	autodiscover.cornerstoneadvisers.com
63.90.79.37	A+PTR	fed.massmutual.com
63.90.79.39	A+PTR	misentrycloudeas.massmutual.com
63.90.79.53	A	lync13-access.massmutual.com
63.90.79.57	A+PTR	isexedgsprprvip01.massmutual.com
63.90.79.96	PTR	dlbvidmediabladext.massmutual.com
63.90.79.111	A+PTR	mmfgonlinevipext.massmutual.com
63.90.79.240	A+PTR	iswmvip01.massmutual.com
63.90.79.243	A+PTR	securemailmm.com
63.90.79.243	A+PTR	www.securemailmm.com