mail.claroip.net.do has no CNAME records.
Question and response
Question
dig mail.claroip.net.do. NS
Answer
The response has no answer records.
Authority
claroip.net.do. 10800 SOA ns1.claro.net.do. hostmaster.claro.net.do. 2016061529 21600 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0