Apex domains cannot have CNAME records.
Question and response
Question
dig up.net. NS
Answer
up.net. 5 NS ns2.up.net.
up.net. 5 NS ns1.up.net.
Authority
The response has no authority records.
Additional
ns1.up.net. 5 A 206.51.127.10
ns2.up.net. 5 A 206.51.127.11
ns1.up.net. 5 AAAA 2001:4a0:0:2:0:0:0:10
ns2.up.net. 5 AAAA 2001:4a0:0:2:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0