Apex domains cannot have CNAME records.
Question and response
Question
dig ns-cnc1.qq.com. NS
Answer
ns-cnc1.qq.com. 5 NS ns-cmn1.qq.com.
ns-cnc1.qq.com. 5 NS ns-tel1.qq.com.
ns-cnc1.qq.com. 5 NS ns-os1.qq.com.
ns-cnc1.qq.com. 5 NS ns-cnc1.qq.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0