Apex domains cannot have CNAME records.
Question and response
Question
dig 77.71.206.in-addr.arpa. NS
Answer
77.71.206.in-addr.arpa. 5 NS ns1.viawest.net.
77.71.206.in-addr.arpa. 5 NS ns2.viawest.net.
Authority
The response has no authority records.
Additional
ns1.viawest.net. 5 A 216.87.64.12
ns2.viawest.net. 5 A 209.170.216.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0