Apex domains cannot have CNAME records.
Question and response
Question
dig escuelalaboral.edu.do. NS
Answer
escuelalaboral.edu.do. 3 NS clint.ns.cloudflare.com.
escuelalaboral.edu.do. 3 NS brenda.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0