Apex domains cannot have CNAME records.
Question and response
Question
dig cem.edu.do. NS
Answer
cem.edu.do. 5 NS n1.intodomain.net.
cem.edu.do. 5 NS n2.intodomain.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0