Apex domains cannot have CNAME records.
Question and response
Question
dig email-od.com. NS
Answer
email-od.com. 4 NS ns-2013.awsdns-59.co.uk.
email-od.com. 4 NS ns-1404.awsdns-47.org.
email-od.com. 4 NS ns-20.awsdns-02.com.
email-od.com. 4 NS ns-715.awsdns-25.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0