Apex domains cannot have CNAME records.
Question and response
Question
dig lumurips.edu.do. NS
Answer
lumurips.edu.do. 2 NS ns8372.hostgator.com.
lumurips.edu.do. 2 NS ns8371.hostgator.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0