Apex domains cannot have CNAME records.
Question and response
Question
dig cdnetworks.net. NS
Answer
cdnetworks.net. 5 NS b.qtlgslbcn.info.
cdnetworks.net. 5 NS b.qtlcdncn.info.
Authority
The response has no authority records.
Additional
b.qtlcdncn.info. 5 A 163.171.128.15
b.qtlcdncn.info. 5 A 163.171.128.75
b.qtlgslbcn.info. 5 A 163.171.128.15
b.qtlgslbcn.info. 5 A 163.171.128.23
b.qtlcdncn.info. 5 AAAA 2a01:53c0:ff02:0:0:0:0:b3
b.qtlcdncn.info. 5 AAAA 2a01:53c0:ff02:0:0:0:0:b4
b.qtlgslbcn.info. 5 AAAA 2a01:53c0:ff02:0:0:0:0:b3
b.qtlgslbcn.info. 5 AAAA 2a01:53c0:ff02:0:0:0:0:b4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0