Robtex

Up: 91.213.142.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 91.213.143.0/25
Down right: 91.213.143.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
91.213.143.0	PTR	avast.com
91.213.143.1	A+PTR	pns.avast.com
91.213.143.2	A+PTR	mx1.avast.com
91.213.143.3	A	mail1.avast.com
91.213.143.4	A	ftp.avast.com
91.213.143.5	PTR	store.avast.com
91.213.143.6	A+PTR	mx2.avast.com
91.213.143.7	A+PTR	public.avast.com
91.213.143.8	A+PTR	mail2.avast.com
91.213.143.11	A+PTR	sns.avast.com
91.213.143.11	A	ns-b.avcdn.net
91.213.143.11	A	ns-b.anon.me
91.213.143.12	PTR	tw.avast.com
91.213.143.12	A	emergencyupdates.ns1.ff.avast.com
91.213.143.13	A	webmail.avast.com
91.213.143.16	A+PTR	sync.avast.com
91.213.143.18	PTR	ntp.avast.com
91.213.143.20	A+PTR	support.avast.com
91.213.143.20	A	support4.avast.com
91.213.143.21	PTR	butr.avast.com
91.213.143.22	PTR	onlinescan.avast.com
91.213.143.22	A	upload.avast.com
91.213.143.23	A+PTR	tw.avast.com
91.213.143.23	A	daisy.avast.com
91.213.143.24	PTR	tp.avast.com
91.213.143.34	A+PTR	stage.api.avast.com
91.213.143.35	PTR	r035.avast.com
91.213.143.35	A	api.avast.com
91.213.143.36	A	dnscache-1.avast.com
91.213.143.36	A	pbxapi.avast.com
91.213.143.42	A	ocelot.avast.com
91.213.143.43	PTR	caracal.avast.com
91.213.143.45	PTR	r045.avast.com
91.213.143.45	A	svn.avast.com
91.213.143.49	A+PTR	cheetah.avast.com
91.213.143.50	A	ftp7.avast.com
91.213.143.51	A+PTR	secure.avast.com
91.213.143.55	A+PTR	lion.avast.com
91.213.143.55	A	lion.asw.cz
91.213.143.56	A+PTR	tiger.avast.com
91.213.143.56	A	intranet.avast.com
91.213.143.56	A	system.avast.com
91.213.143.57	A	goro.avast.com
91.213.143.59	A	fdoper.avast.com
91.213.143.66	A+PTR	puma.avast.com
91.213.143.68	A+PTR	garfield.avast.com
91.213.143.68	A	register.avast.com
91.213.143.70	A	go.avast.com
91.213.143.75	A+PTR	sparky.avast.com
91.213.143.79	PTR	r079.avast.com
91.213.143.79	A	jidder.ossx.net
91.213.143.79	A	5bd58f4f.ossx.net
91.213.143.84	A	n.ns.avast.com
91.213.143.84	A	ns3.avast.com
91.213.143.85	A+PTR	i.ns.avast.com
91.213.143.85	A	ns4.avast.com
91.213.143.91	A+PTR	b.ns.avast.com
91.213.143.111	PTR	r111.avast.com
91.213.143.111	A	logs.avast.com
91.213.143.119	PTR	r119.avast.com
91.213.143.119	A	growshop.avast.com
91.213.143.121	A	ng.avast.com
91.213.143.132	PTR	r132.avast.com
91.213.143.213	PTR	r213.avast.com
91.213.143.214	PTR	nat.2-14-prg.avast.com
91.213.143.218	PTR	r218.avast.com
91.213.143.248	A+PTR	nat.2-48-prg.avast.com
91.213.143.250	A+PTR	nat.2-50-prg.avast.com
91.213.143.251	A+PTR	nat.2-51-prg.avast.com
91.213.143.252	PTR	nat.2-52-prg.avast.com
91.213.143.254	A+PTR	nat.2-54-prg.avast.com
91.213.143.254	A	orig.avast.com
91.213.143.255	PTR	r255.avast.com