Apex domains cannot have CNAME records.
Question and response
Question
dig politecnicoitla.edu.do. NS
Answer
politecnicoitla.edu.do. 2 NS noel.ns.cloudflare.com.
politecnicoitla.edu.do. 2 NS ulla.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0