smtp.k2telecom.net.br has no CNAME records.
Question and response
Question
dig smtp.k2telecom.net.br. NS
Answer
The response has no answer records.
Authority
k2telecom.net.br. 3600 SOA ns1.k2telecom.net.br. ti.k2telecom.net.br. 2026030800 3600 900 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0