mail.interdominios.host has no CNAME records.
Question and response
Question
dig mail.interdominios.host. NS
Answer
The response has no answer records.
Authority
interdominios.host. 10346 SOA dns1.interdominios.com. info.interdominios.com. 1508397963 1080 1800 43200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0