Apex domains cannot have CNAME records.
Question and response
Question
dig smc.net.do. NS
Answer
smc.net.do. 4 NS ns-455.awsdns-56.com.
smc.net.do. 4 NS ns-770.awsdns-32.net.
smc.net.do. 4 NS ns-1255.awsdns-28.org.
smc.net.do. 4 NS ns-1546.awsdns-01.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0