Apex domains cannot have CNAME records.
Question and response
Question
dig seciu.uy. NS
Answer
seciu.uy. 4 NS tacuabe.rau.edu.uy.
seciu.uy. 4 NS seciu.edu.uy.
Authority
The response has no authority records.
Additional
seciu.edu.uy. 4 A 164.73.128.5
tacuabe.rau.edu.uy. 4 A 164.73.128.70
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0