mx2.standardtel.info has no CNAME records.
Question and response
Question
dig mx2.standardtel.info. NS
Answer
The response has no answer records.
Authority
standardtel.info. 29 SOA x.ns.joker.com. hostmaster.joker.com. 2025111452 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0