Apex domains cannot have CNAME records.
Question and response
Question
dig modmancer.com. NS
Answer
modmancer.com. 3 NS ns-1417.awsdns-49.org.
modmancer.com. 3 NS ns-1127.awsdns-12.org.
modmancer.com. 3 NS ns-532.awsdns-02.net.
modmancer.com. 3 NS ns-872.awsdns-45.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0