Apex domains cannot have CNAME records.
Question and response
Question
dig harmony.edu.do. NS
Answer
harmony.edu.do. 5 NS ns-784.awsdns-34.net.
harmony.edu.do. 5 NS ns-1963.awsdns-53.co.uk.
harmony.edu.do. 5 NS ns-327.awsdns-40.com.
harmony.edu.do. 5 NS ns-1405.awsdns-47.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0