Robtex

Up: 210.64.20.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 210.64.21.0/25
Down right: 210.64.21.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
210.64.21.2	PTR	dns2.fb.com.tw
210.64.21.14	PTR	mail.hikalimedia.com
210.64.21.14	PTR	mail.probis.com.tw
210.64.21.14	A	ns1.supalife.com.tw
210.64.21.15	A	mail.hikalimedia.com
210.64.21.53	PTR	h53-210-64-21.fb.com.tw
210.64.21.71	PTR	bigi.com.tw
210.64.21.75	A+PTR	mail.nuee.com.tw
210.64.21.79	PTR	h79-210-64-21.fb.com.tw
210.64.21.80	PTR	mta.t-parts.com.tw
210.64.21.81	PTR	mta.t-parts.com.tw
210.64.21.81	A	t-parts.com.tw
210.64.21.81	A	mail.t-parts.com.tw
210.64.21.85	A	mail.craig.com.tw
210.64.21.94	A	ns3.unitelgroups.com