Apex domains cannot have CNAME records.
Question and response
Question
dig maestrosambulantes.edu.do. NS
Answer
maestrosambulantes.edu.do. 2 NS ns2.siteground.net.
maestrosambulantes.edu.do. 2 NS ns1.siteground.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0