Apex domains cannot have CNAME records.
Question and response
Question
dig cgi.com. NS
Answer
cgi.com. 4 NS ns1.bluecatdns.com.
cgi.com. 4 NS ns1.bluecatdns.org.
cgi.com. 4 NS ns1.f5clouddns.com.
cgi.com. 4 NS ns2.f5clouddns.com.
cgi.com. 4 NS ns1.bluecatdns.net.
Authority
The response has no authority records.
Additional
ns1.bluecatdns.net. 1 A 162.159.9.100
ns1.bluecatdns.org. 1 A 162.159.10.254
ns1.f5clouddns.com. 4 A 107.162.234.197
ns2.f5clouddns.com. 4 A 107.162.176.221
ns1.bluecatdns.net. 1 AAAA 2400:cb00:2049:1:0:0:a29f:964
ns1.bluecatdns.org. 1 AAAA 2400:cb00:2049:1:0:0:a29f:afe
ns1.f5clouddns.com. 4 AAAA 2604:e180:1071:0:0:0:3:1
ns2.f5clouddns.com. 4 AAAA 2604:e180:1071:0:0:ffff:6ba2:b0dd
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0