Apex domains cannot have CNAME records.
Question and response
Question
dig 192-26.28.48.77.in-addr.arpa. NS
Answer
192-26.28.48.77.in-addr.arpa. 5 NS ns1.9t4.net.
192-26.28.48.77.in-addr.arpa. 5 NS ns2.9t4.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0