Apex domains cannot have CNAME records.
Question and response
Question
dig usa.net. NS
Answer
usa.net. 5 NS dnsext01.usa.net.
usa.net. 5 NS ns1.perimeterusa.com.
usa.net. 5 NS ns2.perimeterusa.com.
usa.net. 5 NS dnsext02.usa.net.
Authority
The response has no authority records.
Additional
ns1.perimeterusa.com. 5 A 165.212.182.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0