Apex domains cannot have CNAME records.
Question and response
Question
dig gymmaster.com. NS
Answer
gymmaster.com. 5 NS gns22.cloudns.net.
gymmaster.com. 5 NS gns23.cloudns.net.
gymmaster.com. 5 NS gns24.cloudns.net.
gymmaster.com. 5 NS gns21.cloudns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0