Apex domains cannot have CNAME records.
Question and response
Question
dig invalidemail.com. NS
Answer
invalidemail.com. 5 NS a22-64.akam.net.
invalidemail.com. 5 NS ns2.p201.dns.oraclecloud.net.
invalidemail.com. 5 NS a6-66.akam.net.
invalidemail.com. 5 NS a11-65.akam.net.
invalidemail.com. 5 NS ns3.p201.dns.oraclecloud.net.
invalidemail.com. 5 NS ns1.p201.dns.oraclecloud.net.
invalidemail.com. 5 NS a1-40.akam.net.
invalidemail.com. 5 NS a3-67.akam.net.
invalidemail.com. 5 NS a2-67.akam.net.
invalidemail.com. 5 NS ns4.p201.dns.oraclecloud.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0