Robtex

Up: 31.13.136.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 31.13.136.0/23
Down right: 31.13.138.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
31.13.136.0	A+PTR	host0-136-dinamic-mon.13-31.reteivo.com
31.13.136.19	PTR	host19-136-dinamic-mon.13-31.reteivo.com
31.13.136.116	A	mon.116.136.reteivo.com
31.13.136.116	A	host116-136-static-mon.13-31.reteivo.com
31.13.136.150	A	mon.150.136.reteivo.com
31.13.136.150	A	host150-136-static-mon.13-31.reteivo.com
31.13.136.215	A	host215-136-static-mon.13-31.reteivo.com
31.13.136.231	A+PTR	mon.231.136.reteivo.com
31.13.136.231	A	host231-136-static-mon.13-31.reteivo.com
31.13.136.240	A	host240-136-static-mon.13-31.reteivo.com
31.13.136.250	A	host250-136-static-mon.13-31.reteivo.com
31.13.136.254	A	host254-136-static-mon.13-31.reteivo.com
31.13.136.255	PTR	host255-136-dinamic.13-31.reteivo.com
31.13.137.0	PTR	host0-136-dinamic.13-31.reteivo.com
31.13.137.6	A	mx1.visiaimaging.com
31.13.137.7	PTR	host7-136-dinamic.13-31.reteivo.com
31.13.137.8	PTR	host8-136-dinamic.13-31.reteivo.com
31.13.137.50	PTR	host50-136-dinamic.13-31.reteivo.com
31.13.137.50	A	pratesivini.it
31.13.137.50	A	smtp.pratesivini.it
31.13.137.52	A	fpautopratesi.it
31.13.137.167	A	dns1.winhost.it
31.13.137.168	A	dns2.winhost.it
31.13.137.169	A	mx.winhost.it
31.13.137.212	A	puzzodichianti.com
31.13.137.212	A	videoflashpoint.com
31.13.137.212	A	ilcocco.it
31.13.137.213	A	cpdns01.ivo.cloud
31.13.137.220	PTR	host220-136-dinamic.13-31.reteivo.com
31.13.137.220	A	dtssi.it
31.13.137.251	PTR	mail.nectarine.it
31.13.137.251	A	www.nectarine.it
31.13.137.251	A	nectarine.info
31.13.137.255	PTR	host255-136-dinamic.13-31.reteivo.com
31.13.138.0	A+PTR	host0-138-dinamic.13-31.reteivo.com
31.13.138.7	A+PTR	host7-138-dinamic.13-31.reteivo.com
31.13.138.8	A+PTR	host8-138-dinamic.13-31.reteivo.com
31.13.138.21	A+PTR	host21-138-dinamic.13-31.reteivo.com
31.13.138.32	A+PTR	host32-138-dinamic.13-31.reteivo.com
31.13.138.47	PTR	host47-138-dinamic.13-31.reteivo.com
31.13.138.48	PTR	host48-138-dinamic.13-31.reteivo.com
31.13.138.63	PTR	host63-138-dinamic.13-31.reteivo.com
31.13.138.74	A+PTR	host74-138-dinamic.13-31.reteivo.com
31.13.138.178	PTR	host178-138-dinamic.13-31.reteivo.com
31.13.138.178	A	intranet.celtex.it
31.13.138.255	PTR	host255-138-dinamic.13-31.reteivo.com
31.13.139.0	PTR	host0-139-dinamic.13-31.reteivo.com
31.13.139.21	A	host21-139-static.13-31.reteivo.com
31.13.139.25	A	host25-139-static.13-31.reteivo.com
31.13.139.93	PTR	host93-139-dinamic.13-31.reteivo.com
31.13.139.126	PTR	host126-139-dinamic.13-31.reteivo.com
31.13.139.138	PTR	host138-139-dinamic.13-31.reteivo.com
31.13.139.138	A	host138-139-static.13-31.reteivo.com
31.13.139.228	PTR	host228-139-dinamic.13-31.reteivo.com
31.13.139.255	PTR	host255-139-dinamic.13-31.reteivo.com