Apex domains cannot have CNAME records.
Question and response
Question
dig netdefendersacademy.edu.do. NS
Answer
netdefendersacademy.edu.do. 3 NS ns1045.ui-dns.org.
netdefendersacademy.edu.do. 3 NS ns1045.ui-dns.com.
netdefendersacademy.edu.do. 3 NS ns1045.ui-dns.de.
netdefendersacademy.edu.do. 3 NS ns1045.ui-dns.biz.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0