Apex domains cannot have CNAME records.
Question and response
Question
dig execulink.com. NS
Answer
execulink.com. 5 NS ns.execulink.com.
execulink.com. 5 NS ns-bmi.execulink.com.
Authority
The response has no authority records.
Additional
ns.execulink.com. 5 A 199.166.6.5
ns-bmi.execulink.com. 5 A 216.183.129.9
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0