smtp.hosting.gob.do has no CNAME records.
Question and response
Question
dig smtp.hosting.gob.do. NS
Answer
The response has no answer records.
Authority
hosting.gob.do. 1606 SOA kiki.ns.cloudflare.com. dns.cloudflare.com. 2395765245 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0