Robtex

Up: 199.255.48.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 199.255.52.0/23
Down right: 199.255.54.0/23

IP	Type	Hostname
199.255.52.177	PTR	user-199-255-52-177.lahey.org
199.255.52.223	A+PTR	user-199-255-52-223.lahey.org
199.255.55.71	A	cs.nhs-healthlink.org
199.255.55.73	A+PTR	mail1.nhs-healthlink.org
199.255.55.74	A+PTR	mail2.nhs-healthlink.org
199.255.55.75	PTR	user-199-255-55-75.lahey.org
199.255.55.75	A	support.nhs-healthlink.org
199.255.55.77	A+PTR	netam.nhs-healthlink.org
199.255.55.77	A	bh-emm1.nhs-healthlink.org
199.255.55.77	A	proofpoint.nhs-healthlink.org
199.255.55.159	PTR	user-199-255-55-159.lahey.org
199.255.55.247	PTR	user-199-255-55-247.lahey.org