Apex domains cannot have CNAME records.
Question and response
Question
dig wwwserver.net. NS
Answer
wwwserver.net. 5 NS ns1.is-fun.net.
wwwserver.net. 5 NS ns2.is-fun.net.
Authority
The response has no authority records.
Additional
ns1.is-fun.net. 5 A 212.114.35.78
ns2.is-fun.net. 5 A 192.174.68.100
ns2.is-fun.net. 5 AAAA 2001:67c:1bc:0:0:0:0:100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0