Apex domains cannot have CNAME records.
Question and response
Question
dig dlfslimgym.com. NS
Answer
dlfslimgym.com. 5 NS ns-1204.awsdns-22.org.
dlfslimgym.com. 5 NS ns-922.awsdns-51.net.
dlfslimgym.com. 5 NS ns-519.awsdns-00.net.
dlfslimgym.com. 5 NS ns-952.awsdns-55.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0