Apex domains cannot have CNAME records.
Question and response
Question
dig 97.220.65.in-addr.arpa. NS
Answer
97.220.65.in-addr.arpa. 5 NS auth20.ns.wcom.com.
97.220.65.in-addr.arpa. 5 NS auth10.ns.wcom.com.
Authority
The response has no authority records.
Additional
auth10.ns.wcom.com. 4 A 198.6.100.21
auth20.ns.wcom.com. 4 A 198.6.100.37
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0