Apex domains cannot have CNAME records.
Question and response
Question
dig yu.net. NS
Answer
yu.net. 5 NS ns2.yu.net.
yu.net. 5 NS ns3.yu.net.
yu.net. 5 NS ns1.yu.net.
Authority
The response has no authority records.
Additional
ns1.yu.net. 5 A 194.247.196.52
ns2.yu.net. 5 A 194.247.196.53
ns3.yu.net. 5 A 194.247.196.54
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0