Apex domains cannot have CNAME records.
Question and response
Question
dig acserviceall.com. NS
Answer
acserviceall.com. 4 NS ns22.ecomsiam.com.
acserviceall.com. 4 NS ns21.ecomsiam.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0