Apex domains cannot have CNAME records.
Question and response
Question
dig linktelecom.com.py. NS
Answer
linktelecom.com.py. 5 NS ns1.linktelecom.com.py.
linktelecom.com.py. 5 NS ns2.linktelecom.com.py.
Authority
The response has no authority records.
Additional
ns1.linktelecom.com.py. 5 A 190.93.179.2
ns2.linktelecom.com.py. 5 A 190.93.179.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0