Apex domains cannot have CNAME records.
Question and response
Question
dig expert. NS
Answer
expert. 5 NS v0n3.nic.expert.
expert. 5 NS v2n1.nic.expert.
expert. 5 NS v0n1.nic.expert.
expert. 5 NS v0n0.nic.expert.
expert. 5 NS v0n2.nic.expert.
expert. 5 NS v2n0.nic.expert.
Authority
The response has no authority records.
Additional
v0n0.nic.expert. 172528 A 65.22.32.4
v0n1.nic.expert. 67596 A 65.22.33.4
v0n2.nic.expert. 172528 A 65.22.34.4
v0n3.nic.expert. 172528 A 161.232.16.4
v2n0.nic.expert. 172528 A 65.22.35.4
v2n1.nic.expert. 172528 A 161.232.17.4
v0n0.nic.expert. 172528 AAAA 2a01:8840:22:0:0:0:0:4
v0n1.nic.expert. 67596 AAAA 2a01:8840:23:0:0:0:0:4
v0n2.nic.expert. 172528 AAAA 2a01:8840:24:0:0:0:0:4
v0n3.nic.expert. 172528 AAAA 2a01:8840:fa:0:0:0:0:4
v2n0.nic.expert. 172528 AAAA 2a01:8840:25:0:0:0:0:4
v2n1.nic.expert. 172528 AAAA 2a01:8840:fb:0:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0