Apex domains cannot have CNAME records.
Question and response
Question
dig colegiocce.edu.do. NS
Answer
colegiocce.edu.do. 4 NS hgns1.hostgator.com.
colegiocce.edu.do. 4 NS hgns2.hostgator.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0