Apex domains cannot have CNAME records.
Question and response
Question
dig rackmy.com. NS
Answer
rackmy.com. 4 NS ns2.rackmy.com.
rackmy.com. 4 NS ns1.rackmy.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0