Apex domains cannot have CNAME records.
Question and response
Question
dig nicusa.com. NS
Answer
nicusa.com. 5 NS ns7.nicusa.com.
nicusa.com. 5 NS ns6.nicusa.com.
nicusa.com. 5 NS ns5.nicusa.com.
nicusa.com. 5 NS ns8.nicusa.com.
Authority
The response has no authority records.
Additional
ns5.nicusa.com. 5 A 206.17.31.80
ns6.nicusa.com. 5 A 63.241.232.80
ns7.nicusa.com. 5 A 206.17.31.81
ns8.nicusa.com. 5 A 63.241.232.81
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0