Apex domains cannot have CNAME records.
Question and response
Question
dig shrm.org. NS
Answer
shrm.org. 4 NS ns-654.awsdns-17.net.
shrm.org. 4 NS ns-202.awsdns-25.com.
shrm.org. 4 NS ns-1938.awsdns-50.co.uk.
shrm.org. 4 NS ns-1127.awsdns-12.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0