Apex domains cannot have CNAME records.
Question and response
Question
dig edu.uy. NS
Answer
edu.uy. 5 NS ns.dns.br.
edu.uy. 5 NS a.lactld.org.
edu.uy. 5 NS ns2.anteldata.com.uy.
edu.uy. 5 NS seciu.edu.uy.
edu.uy. 5 NS ultra.edu.uy.
edu.uy. 5 NS ns1.anteldata.com.uy.
Authority
The response has no authority records.
Additional
a.lactld.org. 3 A 200.0.68.10
a.lactld.org. 3 AAAA 2801:14:a000:0:0:0:0:10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0