Apex domains cannot have CNAME records.
Question and response
Question
dig macys.com. NS
Answer
macys.com. 3 NS a24-65.akam.net.
macys.com. 3 NS a13-66.akam.net.
macys.com. 3 NS a14-67.akam.net.
macys.com. 3 NS a5-66.akam.net.
macys.com. 3 NS a1-135.akam.net.
macys.com. 3 NS a22-64.akam.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0