Apex domains cannot have CNAME records.
Question and response
Question
dig NIC.gdn. NS
Answer
NIC.gdn. 5 NS ns3.NIC.gdn.
NIC.gdn. 5 NS ns1.NIC.gdn.
Authority
The response has no authority records.
Additional
ns1.nic.gdn. 118693 A 194.0.25.18
ns3.nic.gdn. 165082 A 194.0.26.11
ns1.nic.gdn. 118693 AAAA 2001:678:20:0:0:0:0:18
ns3.nic.gdn. 165082 AAAA 2001:67c:10e0:0:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0