smtp3.execulink.net has no CNAME records.
Question and response
Question
dig smtp3.execulink.net. NS
Answer
The response has no answer records.
Authority
execulink.net. 1519 SOA mallet.execulink.net. sysadmin.execulink.com. 2026022001 192873 300 604800 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0