Apex domains cannot have CNAME records.
Question and response
Question
dig verizon.com. NS
Answer
verizon.com. 5 NS a26-67.akam.net.
verizon.com. 5 NS a1-18.akam.net.
verizon.com. 5 NS a13-67.akam.net.
verizon.com. 5 NS a9-67.akam.net.
verizon.com. 5 NS a12-65.akam.net.
verizon.com. 5 NS a24-66.akam.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0