smtp2.educando.edu.do has no CNAME records.
Question and response
Question
dig smtp2.educando.edu.do. NS
Answer
The response has no answer records.
Authority
educando.edu.do. 3361 SOA ns1-06.azure-dns.com. hostmaster. 88 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0