Apex domains cannot have CNAME records.
Question and response
Question
dig customer-auth.net. NS
Answer
customer-auth.net. 5 NS c.customer-auth.net.
customer-auth.net. 5 NS d.customer-auth.net.
customer-auth.net. 5 NS a.customer-auth.net.
customer-auth.net. 5 NS b.customer-auth.net.
Authority
The response has no authority records.
Additional
a.customer-auth.net. 5 A 62.116.159.4
b.customer-auth.net. 5 A 217.160.113.37
c.customer-auth.net. 5 A 89.146.248.4
d.customer-auth.net. 5 A 74.208.254.4
b.customer-auth.net. 5 AAAA 2001:8d8:580:401:217:160:113:37
c.customer-auth.net. 5 AAAA 2a01:130:2000:118:89:146:248:4
d.customer-auth.net. 5 AAAA 2607:f1c0:1800:8091:74:208:254:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0