Apex domains cannot have CNAME records.
Question and response
Question
dig s2bnet.net. NS
Answer
s2bnet.net. 5 NS ns-754.awsdns-30.net.
s2bnet.net. 5 NS ns-1400.awsdns-47.org.
s2bnet.net. 5 NS ns-1698.awsdns-20.co.uk.
s2bnet.net. 5 NS ns-99.awsdns-12.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0