Robtex

Up: 212.58.20.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 212.58.21.0/25
Down right: 212.58.21.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
212.58.21.0	PTR	net.doruk.net.tr
212.58.21.2	PTR	mail.tezmaksan.com
212.58.21.2	A	mail.tezmak.com.tr
212.58.21.37	PTR	mail.datassist.com.tr
212.58.21.37	A	imap.datassist.com.tr
212.58.21.39	A	isguvencesi.com
212.58.21.41	A	ynb.datassist.com.tr
212.58.21.43	PTR	rev.43.21.58.212.doruk.net.tr
212.58.21.43	A	net-brut.com
212.58.21.50	A+PTR	datassist.doruk.net.tr
212.58.21.52	PTR	rev.52.21.58.212.doruk.net.tr
212.58.21.52	A	net-brut.com
212.58.21.52	A	turkishlabourlaw.com
212.58.21.53	A	mevzuatkulubu.com
212.58.21.58	A+PTR	datassistdb.doruk.net.tr
212.58.21.58	A	bordrojet.com
212.58.21.61	A	61.21.58.212.drk.ist.tr.net-brut.com
212.58.21.68	PTR	www.turassist.com
212.58.21.70	PTR	mail.turasist.com
212.58.21.70	A	mail.turassist.com
212.58.21.74	PTR	rev.74.21.58.212.doruk.net.tr
212.58.21.100	PTR	rev.100.21.58.212.doruk.net.tr
212.58.21.100	A	cebit-bilisim.com
212.58.21.100	A	www.cebitbilisim.com
212.58.21.134	PTR	rev.134.21.58.212.doruk.net.tr
212.58.21.134	A	opr.fu.com.tr
212.58.21.140	A+PTR	mail3.fu.com.tr
212.58.21.193	A+PTR	mail.habas.com.tr
212.58.21.195	PTR	mail2.habas.com.tr
212.58.21.221	A	veritatelekom.com
212.58.21.242	PTR	rev.242.21.58.212.doruk.net.tr
212.58.21.242	A	bilgi.university
212.58.21.242	A	bahcesehir.mba
212.58.21.255	PTR	bcast.doruk.net.tr