Apex domains cannot have CNAME records.
Question and response
Question
dig asuscomm.com. NS
Answer
asuscomm.com. 5 NS ns-nw.asuscomm.com.
Authority
The response has no authority records.
Additional
ns-nw.asuscomm.com. 5 A 52.250.42.40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0