Apex domains cannot have CNAME records.
Question and response
Question
dig net.uy. NS
Answer
net.uy. 5 NS a.lactld.org.
net.uy. 5 NS ns1.anteldata.com.uy.
net.uy. 5 NS seciu.edu.uy.
net.uy. 5 NS ns2.anteldata.com.uy.
net.uy. 5 NS ns.dns.br.
net.uy. 5 NS ultra.edu.uy.
Authority
The response has no authority records.
Additional
a.lactld.org. 2 A 200.0.68.10
ns1.anteldata.com.uy. 172524 A 200.40.30.254
ns2.anteldata.com.uy. 172524 A 200.40.220.254
a.lactld.org. 2 AAAA 2801:14:a000:0:0:0:0:10
ns1.anteldata.com.uy. 172524 AAAA 2800:a0:53:1001:0:0:0:1
ns2.anteldata.com.uy. 172524 AAAA 2800:a0:53:1002:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0