Apex domains cannot have CNAME records.
Question and response
Question
dig centroeducativocaracoli.edu.do. NS
Answer
centroeducativocaracoli.edu.do. 5 NS pns3.cloudns.net.
centroeducativocaracoli.edu.do. 5 NS pns2.cloudns.net.
centroeducativocaracoli.edu.do. 5 NS pns1.cloudns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0