Apex domains cannot have CNAME records.
Question and response
Question
dig gc.onl. NS
Answer
gc.onl. 5 NS ns2.gcdn.services.
gc.onl. 5 NS ns-733.awsdns-27.net.
gc.onl. 5 NS ns1.gcorelabs.net.
gc.onl. 5 NS ns-500.awsdns-62.com.
Authority
The response has no authority records.
Additional
ns1.gcorelabs.net. 3 A 92.223.100.53
ns1.gcorelabs.net. 3 A 92.223.100.253
ns2.gcdn.services. 3 A 92.223.77.53
ns2.gcdn.services. 3 A 92.223.77.253
ns-500.awsdns-62.com. 3 A 205.251.193.244
ns-733.awsdns-27.net. 3 A 205.251.194.221
ns1.gcorelabs.net. 3 AAAA 2a03:90c0:9990:0:0:0:0:1053
ns2.gcdn.services. 3 AAAA 2a03:90c0:9990:0:0:0:0:2053
ns-500.awsdns-62.com. 3 AAAA 2600:9000:5301:f400:0:0:0:1
ns-733.awsdns-27.net. 3 AAAA 2600:9000:5302:dd00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0