Apex domains cannot have CNAME records.
Question and response
Question
dig sbi.edu.do. NS
Answer
sbi.edu.do. 5 NS ns35.dnns.net.
sbi.edu.do. 5 NS ns34.dnns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0