Apex domains cannot have CNAME records.
Question and response
Question
dig xyz. NS
Answer
xyz. 5 NS z.nic.xyz.
xyz. 5 NS generationxyz.nic.xyz.
xyz. 5 NS x.nic.xyz.
xyz. 5 NS y.nic.xyz.
Authority
The response has no authority records.
Additional
x.nic.xyz. 140161 A 194.169.218.42
y.nic.xyz. 140161 A 185.24.64.42
z.nic.xyz. 140161 A 212.18.248.42
generationxyz.nic.xyz. 140161 A 212.18.249.42
x.nic.xyz. 140161 AAAA 2001:67c:13cc:0:0:0:1:42
y.nic.xyz. 140161 AAAA 2a04:2b00:13cc:0:0:0:1:42
z.nic.xyz. 140161 AAAA 2a04:2b00:13ee:0:0:0:0:42
generationxyz.nic.xyz. 140161 AAAA 2a04:2b00:13ff:0:0:0:0:42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0