Apex domains cannot have CNAME records.
Question and response
Question
dig siana.edu.do. NS
Answer
siana.edu.do. 2 NS ns8501.hostgator.com.
siana.edu.do. 2 NS ns8502.hostgator.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0