Apex domains cannot have CNAME records.
Question and response
Question
dig amc.edu.do. NS
Answer
amc.edu.do. 5 NS ns-1385.awsdns-45.org.
amc.edu.do. 5 NS ns-1866.awsdns-41.co.uk.
amc.edu.do. 5 NS ns-27.awsdns-03.com.
amc.edu.do. 5 NS ns-1007.awsdns-61.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0