Apex domains cannot have CNAME records.
Question and response
Question
dig group. NS
Answer
group. 5 NS v0n0.nic.group.
group. 5 NS v2n1.nic.group.
group. 5 NS v0n2.nic.group.
group. 5 NS v0n3.nic.group.
group. 5 NS v2n0.nic.group.
group. 5 NS v0n1.nic.group.
Authority
The response has no authority records.
Additional
v0n0.nic.group. 156344 A 65.22.20.2
v0n1.nic.group. 156344 A 65.22.21.2
v0n2.nic.group. 171834 A 65.22.22.2
v0n3.nic.group. 156344 A 161.232.10.2
v2n0.nic.group. 156344 A 65.22.23.2
v2n1.nic.group. 156344 A 161.232.11.2
v0n0.nic.group. 156344 AAAA 2a01:8840:16:0:0:0:0:2
v0n1.nic.group. 156344 AAAA 2a01:8840:17:0:0:0:0:2
v0n2.nic.group. 171834 AAAA 2a01:8840:18:0:0:0:0:2
v0n3.nic.group. 156344 AAAA 2a01:8840:f4:0:0:0:0:2
v2n0.nic.group. 156344 AAAA 2a01:8840:19:0:0:0:0:2
v2n1.nic.group. 156344 AAAA 2a01:8840:f5:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0