Apex domains cannot have CNAME records.
Question and response
Question
dig gcdn.services. NS
Answer
gcdn.services. 2 NS ns1.gcdn.services.
gcdn.services. 2 NS ns2.gcdn.services.
gcdn.services. 2 NS ns3.gcdn.services.
gcdn.services. 2 NS ns4.gcdn.services.
Authority
The response has no authority records.
Additional
ns1.gcdn.services. 2 A 92.223.100.53
ns2.gcdn.services. 2 A 92.223.77.53
ns1.gcdn.services. 2 AAAA 2a03:90c0:9990:0:0:0:0:1053
ns2.gcdn.services. 2 AAAA 2a03:90c0:9990:0:0:0:0:2053
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0