Apex domains cannot have CNAME records.
Question and response
Question
dig lumuri.edu.do. NS
Answer
lumuri.edu.do. 1 NS ns8372.hostgator.com.
lumuri.edu.do. 1 NS ns8371.hostgator.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0