Apex domains cannot have CNAME records.
Question and response
Question
dig ckfmarket.us.com. NS
Answer
ckfmarket.us.com. 4 NS sage.ns.cloudflare.com.
ckfmarket.us.com. 4 NS may.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
may.ns.cloudflare.com. 4 A 108.162.192.135
may.ns.cloudflare.com. 4 A 172.64.32.135
may.ns.cloudflare.com. 4 A 173.245.58.135
sage.ns.cloudflare.com. 4 A 108.162.195.236
sage.ns.cloudflare.com. 4 A 162.159.44.236
sage.ns.cloudflare.com. 4 A 172.64.35.236
may.ns.cloudflare.com. 4 AAAA 2606:4700:50:0:0:0:adf5:3a87
may.ns.cloudflare.com. 4 AAAA 2803:f800:50:0:0:0:6ca2:c087
may.ns.cloudflare.com. 4 AAAA 2a06:98c1:50:0:0:0:ac40:2087
sage.ns.cloudflare.com. 4 AAAA 2606:4700:58:0:0:0:a29f:2cec
sage.ns.cloudflare.com. 4 AAAA 2803:f800:50:0:0:0:6ca2:c3ec
sage.ns.cloudflare.com. 4 AAAA 2a06:98c1:50:0:0:0:ac40:23ec
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0