Apex domains cannot have CNAME records.
Question and response
Question
dig abirnet2.com. NS
Answer
abirnet2.com. 2 NS ns4bht.name.com.
abirnet2.com. 2 NS ns1mtw.name.com.
abirnet2.com. 2 NS ns2bkr.name.com.
abirnet2.com. 2 NS ns3flt.name.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0