Apex domains cannot have CNAME records.
Question and response
Question
dig pub. NS
Answer
pub. 5 NS v0n3.nic.pub.
pub. 5 NS v0n1.nic.pub.
pub. 5 NS v0n0.nic.pub.
pub. 5 NS v0n2.nic.pub.
pub. 5 NS v2n1.nic.pub.
pub. 5 NS v2n0.nic.pub.
Authority
The response has no authority records.
Additional
v0n0.nic.pub. 172377 A 65.22.28.7
v0n1.nic.pub. 144357 A 65.22.29.7
v0n2.nic.pub. 172377 A 65.22.30.7
v0n3.nic.pub. 172377 A 161.232.14.7
v2n0.nic.pub. 172377 A 65.22.31.7
v2n1.nic.pub. 172377 A 161.232.15.7
v0n0.nic.pub. 172377 AAAA 2a01:8840:1e:0:0:0:0:7
v0n1.nic.pub. 144357 AAAA 2a01:8840:1f:0:0:0:0:7
v0n2.nic.pub. 172377 AAAA 2a01:8840:20:0:0:0:0:7
v0n3.nic.pub. 172377 AAAA 2a01:8840:f8:0:0:0:0:7
v2n0.nic.pub. 172377 AAAA 2a01:8840:21:0:0:0:0:7
v2n1.nic.pub. 172377 AAAA 2a01:8840:f9:0:0:0:0:7
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0