Apex domains cannot have CNAME records.
Question and response
Question
dig cis.edu.do. NS
Answer
cis.edu.do. 5 NS ns6166.hostgator.com.
cis.edu.do. 5 NS ns6165.hostgator.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0