etrn-com.d.mx.etrn.com has no CNAME records.
Question and response
Question
dig etrn-com.d.mx.etrn.com. NS
Answer
The response has no answer records.
Authority
mx.etrn.com. 3600 SOA ns1.fmt.etrn.com. hostmaster.etrn.com. 2023072473 1800 900 1814400 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0