Apex domains cannot have CNAME records.
Question and response
Question
dig xck1688.com. NS
Answer
xck1688.com. 1 NS ns-924.awsdns-51.net.
xck1688.com. 1 NS ns-1224.awsdns-25.org.
xck1688.com. 1 NS ns-1860.awsdns-40.co.uk.
xck1688.com. 1 NS ns-2000.awsdns-58.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0