mail.aster.net.do has no CNAME records.
Question and response
Question
dig mail.aster.net.do. NS
Answer
The response has no answer records.
Authority
aster.net.do. 3361 SOA aster.net.do. jmarte\@aster.net.do. 2023092203 3600 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0