mx2.gblnet.net has no CNAME records.
Question and response
Question
dig mx2.gblnet.net. NS
Answer
The response has no answer records.
Authority
gblnet.net. 4496 SOA ns.gblnet.net. vvv.gblnet.net. 2026021602 10800 1200 1209600 259200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0