Robtex

Up: 212.54.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 212.54.40.0/23
Down right: 212.54.42.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
212.54.40.4	PTR	login.tb.aaa.iss.as9143.net
212.54.40.5	PTR	members.tb.webspace.iss.as9143.net
212.54.40.5	A	smitja.at.quicknet.nl
212.54.40.5	A	keona.nl
212.54.40.10	A	wifiportal.ziggo.nl
212.54.40.12	PTR	news.ziggo.nl
212.54.40.12	A	news.tilbu1.nb.home.nl
212.54.40.13	PTR	news.ziggozakelijk.nl
212.54.40.25	A+PTR	dns-resolver1-tb-anycast.ziggo.nl
212.54.40.25	A	dns.tb.iss.as9143.net
212.54.40.25	A	yurroon.nl
212.54.40.26	PTR	ns1.tb.iss.as9143.net
212.54.40.100	PTR	siptrunk-sipt.ziggo.nl
212.54.40.100	A	unify-openscape-sipt1.ziggo.nl
212.54.40.103	A	psip4.sipnl.net
212.54.40.103	A	sipnl.net
212.54.40.103	A	psip1.sipnl.net
212.54.40.109	A	sipnl.net
212.54.40.109	A	siptrunk-sipt.ziggo.nl
212.54.40.109	A	voip.sipnl.net
212.54.41.196	A+PTR	gtm1.tb.iss.as9143.net
212.54.41.197	A+PTR	gtm2.tb.iss.as9143.net
212.54.41.230	A+PTR	dns3.tb.iss.as9143.net
212.54.41.231	A+PTR	dns4.tb.iss.as9143.net
212.54.41.232	A+PTR	dns5.tb.iss.as9143.net
212.54.41.233	A+PTR	dns6.tb.iss.as9143.net
212.54.41.234	PTR	dns7.tb.iss.as9143.net
212.54.41.235	A+PTR	dns8.tb.iss.as9143.net
212.54.42.1	PTR	mail-pub-vips-gw.tb.mail.iss.as9143.net
212.54.42.4	A+PTR	pop.tb.mail.iss.as9143.net
212.54.42.4	A	pa1apw.net
212.54.42.5	PTR	webmail.tb.mail.iss.as9143.net
212.54.42.5	A	webmail.mail.gtm.iss.as9143.net
212.54.42.5	A	mail.biamic.nl
212.54.42.8	A+PTR	mx.tb.mail.iss.as9143.net
212.54.42.8	PTR	mx.gn.mail.iss.as9143.net
212.54.42.8	A	mx.mail.gtm.iss.as9143.net
212.54.42.9	PTR	smtp.tb.mail.iss.as9143.net
212.54.42.12	PTR	mcldap.tb.mail.iss.as9143.net
212.54.42.12	A	home-webmail.gn.mail.iss.as9143.net
212.54.42.13	A+PTR	md.tb.mail.iss.as9143.net
212.54.42.13	A	webmail.multikabel.nl
212.54.42.13	A	multikabel-webmail.gn.mail.iss.as9143.net
212.54.42.15	PTR	smtp-b2b.tb.mail.iss.as9143.net
212.54.42.16	A+PTR	webmail2.tb.mail.iss.as9143.net
212.54.42.19	A+PTR	pop-new.tb.mail.iss.as9143.net
212.54.42.19	A	pop.casema.nl
212.54.42.19	A	pop.home.nl
212.54.42.20	PTR	imap.tb.mail.iss.as9143.net
212.54.42.20	A	imap.ziggo.nl
212.54.42.24	A+PTR	cloud.tb.mail.iss.as9143.net
212.54.42.24	A	webmail.nl
212.54.42.24	A	email.ziggo.nl
212.54.42.34	A+PTR	legacymail.tb.mail.iss.as9143.net
212.54.42.34	A	pop.chello.nl
212.54.42.34	A	pop.upcmail.nl
212.54.42.44	A	mta4.tb.mail.iss.as9143.net
212.54.42.50	A+PTR	mta3z1.tb.mail.iss.as9143.net
212.54.42.50	A	mx.acc.mail.iss.as9143.net
212.54.42.50	A	mx.tb.acc.mail.iss.as9143.net
212.54.42.92	PTR	slb2-vlan155.tb.iss.as9143.net
212.54.42.92	A	slb2-mail-webmail.tb.mail.iss.as9143.net
212.54.42.100	A+PTR	mx1.tb.mail.iss.as9143.net
212.54.42.101	A+PTR	mx2.tb.mail.iss.as9143.net
212.54.42.102	A	mx3.tb.mail.iss.as9143.net
212.54.42.105	A	smtp1.tb.mail.iss.as9143.net
212.54.42.109	A+PTR	smtp5.tb.mail.iss.as9143.net
212.54.42.116	A+PTR	lsmtp2.tb.mail.iss.as9143.net
212.54.42.132	A	smtp1.tb.mail.iss.as9143.net
212.54.42.133	PTR	smtp2.tb.mail.iss.as9143.net
212.54.42.133	A	smtp9.tb.mail.iss.as9143.net
212.54.42.135	PTR	smtp4.tb.mail.iss.as9143.net
212.54.42.135	A	smtp11.tb.mail.iss.as9143.net
212.54.42.136	PTR	smtp5.tb.mail.iss.as9143.net
212.54.42.137	PTR	smtp6.tb.mail.iss.as9143.net
212.54.42.139	A+PTR	mx11.tb.mail.iss.as9143.net
212.54.42.140	A+PTR	mx12.tb.mail.iss.as9143.net
212.54.42.143	A+PTR	mx16.tb.mail.iss.as9143.net
212.54.42.144	A+PTR	mx17.tb.mail.iss.as9143.net
212.54.42.145	A+PTR	mx18.tb.mail.iss.as9143.net
212.54.42.147	A+PTR	mx14.tb.mail.iss.as9143.net
212.54.42.148	A+PTR	mx20.tb.mail.iss.as9143.net
212.54.42.149	PTR	mx21.tb.mail.iss.as9143.net
212.54.42.150	A+PTR	mx22.tb.mail.iss.as9143.net
212.54.42.151	PTR	mx23.tb.mail.iss.as9143.net
212.54.42.152	PTR	mx24.tb.mail.iss.as9143.net
212.54.42.164	A+PTR	smtpq1.tb.mail.iss.as9143.net
212.54.42.165	A+PTR	smtpq2.tb.mail.iss.as9143.net
212.54.42.166	A+PTR	smtpq3.tb.mail.iss.as9143.net
212.54.42.167	A+PTR	smtpq4.tb.mail.iss.as9143.net
212.54.42.168	PTR	smtpq5.tb.mail.iss.as9143.net
212.54.42.169	A+PTR	smtpq6.tb.mail.iss.as9143.net
212.54.42.189	A	slb1-mail-smtpq.tb.mail.iss.as9143.net
212.54.42.238	A	rbldns2.tb.mail.iss.as9143.net
212.54.42.242	A+PTR	dcdns3.tb.mail.iss.as9143.net
212.54.43.0	PTR	pub-vips-net26.hgv.b2b.iss.as9143.net
212.54.43.1	PTR	pub-vips-gw.hgv.b2b.iss.as9143.net
212.54.43.8	A	mx2.atwork.nl
212.54.43.8	A	mx.ziggozakelijk.nl
212.54.43.8	A	mx3.atwork.nl
212.54.43.9	PTR	smtp.hgv.b2b.iss.as9143.net
212.54.43.30	A+PTR	imap.ziggozakelijk.nl
212.54.43.32	PTR	smtp.ziggozakelijk.nl
212.54.43.35	A+PTR	imap.atwork.nl
212.54.43.36	A+PTR	pop.atwork.nl
212.54.43.36	A	pop3.atwork.nl
212.54.43.37	PTR	smtp.atwork.nl
212.54.43.37	A	relay2.atwork.nl
212.54.43.37	A	relay1.atwork.nl
212.54.43.38	PTR	webmail.atwork.nl
212.54.43.46	A	pop3.schoolconnect.nu
212.54.43.46	A	pop.schoolconnect.nu
212.54.43.47	PTR	smtp.schoolconnect.nu
212.54.43.48	PTR	webmail.schoolconnect.nu
212.54.43.49	A+PTR	webloket.schoolconnect.nu
212.54.43.64	PTR	smtp-net26.hgv.b2b.iss.as9143.net
212.54.43.104	A+PTR	sbc200-sig607-2.tb.tss.as9143.net
212.54.43.104	A	mvoipb2.ziggo.nl
212.54.43.128	A	mx-net28.hgv.b2b.iss.as9143.net
212.54.43.150	A+PTR	smtpq1.hgv.b2b.iss.as9143.net
212.54.43.172	PTR	slb2-vlan110.hgv.b2b.iss.as9143.net
212.54.43.236	A+PTR	ns3.as9143.net
212.54.43.237	A+PTR	ns4.as9143.net