Apex domains cannot have CNAME records.
Question and response
Question
dig unicaribe.edu.do. NS
Answer
unicaribe.edu.do. 5 NS ns-1684.awsdns-18.co.uk.
unicaribe.edu.do. 5 NS ns-151.awsdns-18.com.
unicaribe.edu.do. 5 NS ns-984.awsdns-59.net.
unicaribe.edu.do. 5 NS ns-1136.awsdns-14.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0