Apex domains cannot have CNAME records.
Question and response
Question
dig gdn. NS
Answer
gdn. 2 NS ns3.nic.gdn.
gdn. 2 NS ns4.nic.gdn.
gdn. 2 NS ns1.nic.gdn.
Authority
The response has no authority records.
Additional
ns1.nic.gdn. 172686 A 194.0.25.18
ns3.nic.gdn. 172686 A 194.0.26.11
ns4.nic.gdn. 160879 A 194.0.24.11
ns1.nic.gdn. 172686 AAAA 2001:678:20:0:0:0:0:18
ns3.nic.gdn. 172686 AAAA 2001:67c:10e0:0:0:0:0:11
ns4.nic.gdn. 160879 AAAA 2001:678:24:0:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0