mx2.atsgestion.com has no CNAME records.
Question and response
Question
dig mx2.atsgestion.com. NS
Answer
The response has no answer records.
Authority
atsgestion.com. 127 SOA ns1-auth.etb.net.co. postmaster.etb.net.co. 49 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0