Apex domains cannot have CNAME records.
Question and response
Question
dig subnet16.190.71.64.in-addr.arpa. NS
Answer
subnet16.190.71.64.in-addr.arpa. 4 NS sdn.iecc.com.
subnet16.190.71.64.in-addr.arpa. 4 NS ns1.everett.org.
subnet16.190.71.64.in-addr.arpa. 4 NS ns2.everett.org.
Authority
The response has no authority records.
Additional
ns1.everett.org. 4 A 66.220.13.229
ns2.everett.org. 4 A 66.220.13.230
sdn.iecc.com. 4 A 108.161.135.154
sdn.iecc.com. 4 AAAA 2606:4300:0:4:0:0:0:106e
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0