Apex domains cannot have CNAME records.
Question and response
Question
dig iterom.edu.do. NS
Answer
iterom.edu.do. 5 NS dns2053b.trouble-free.net.
iterom.edu.do. 5 NS dns2053a.trouble-free.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0