Apex domains cannot have CNAME records.
Question and response
Question
dig 128-191.167.106.59.in-addr.arpa. NS
Answer
128-191.167.106.59.in-addr.arpa. 4 NS ns01.xbit.jp.
128-191.167.106.59.in-addr.arpa. 4 NS ns02.xbit.jp.
Authority
The response has no authority records.
Additional
ns01.xbit.jp. 4 A 59.106.35.125
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0