Apex domains cannot have CNAME records.
Question and response
Question
dig secureserver.net. NS
Answer
secureserver.net. 2 NS a8-67.akam.net.
secureserver.net. 2 NS a11-64.akam.net.
secureserver.net. 2 NS a1-245.akam.net.
secureserver.net. 2 NS a20-65.akam.net.
secureserver.net. 2 NS cns1.secureserver.net.
secureserver.net. 2 NS a6-66.akam.net.
secureserver.net. 2 NS a9-67.akam.net.
secureserver.net. 2 NS cns2.secureserver.net.
Authority
The response has no authority records.
Additional
cns1.secureserver.net. 2 A 97.74.96.100
cns2.secureserver.net. 2 A 173.201.64.100
cns1.secureserver.net. 2 AAAA 2603:5:2100:0:0:0:0:64
cns2.secureserver.net. 2 AAAA 2603:5:2200:0:0:0:0:64
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0