Apex domains cannot have CNAME records.
Question and response
Question
dig ai270.net. NS
Answer
ai270.net. 5 NS ns1.lcn.com.
ai270.net. 5 NS ns0.lcn.com.
ai270.net. 5 NS ns2.lcn.com.
Authority
The response has no authority records.
Additional
ns0.lcn.com. 5 A 195.110.124.234
ns1.lcn.com. 5 A 85.233.160.69
ns2.lcn.com. 5 A 91.186.2.8
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0