Apex domains cannot have CNAME records.
Question and response
Question
dig layer6.net. NS
Answer
layer6.net. 4 NS ns2.layer6.net.
layer6.net. 4 NS ns4.layer6.net.
layer6.net. 4 NS ns1.layer6.net.
layer6.net. 4 NS ns3.layer6.net.
Authority
The response has no authority records.
Additional
ns1.layer6.net. 4 A 5.34.180.212
ns1.layer6.net. 4 A 217.12.221.175
ns2.layer6.net. 4 A 195.123.213.192
ns2.layer6.net. 4 A 195.123.225.13
ns3.layer6.net. 4 A 195.123.243.46
ns3.layer6.net. 4 A 195.123.245.45
ns4.layer6.net. 4 A 195.123.233.95
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0