Apex domains cannot have CNAME records.
Question and response
Question
dig adlermails.com. NS
Answer
adlermails.com. 5 NS ns-414.awsdns-51.com.
adlermails.com. 5 NS ns-224.awsdns-28.com.
adlermails.com. 5 NS ns-1462.awsdns-54.org.
adlermails.com. 5 NS ns-510.awsdns-63.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0