Apex domains cannot have CNAME records.
Question and response
Question
dig impulsa.edu.do. NS
Answer
impulsa.edu.do. 5 NS rita.ns.cloudflare.com.
impulsa.edu.do. 5 NS kai.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0