Apex domains cannot have CNAME records.
Question and response
Question
dig zabco.net. NS
Answer
zabco.net. 1 NS ns1.zabco.net.
zabco.net. 1 NS ns2.zabco.net.
Authority
The response has no authority records.
Additional
ns1.zabco.net. 1 A 208.123.210.2
ns2.zabco.net. 1 A 206.189.183.158
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0