Apex domains cannot have CNAME records.
Question and response
Question
dig vicugna.org. NS
Answer
vicugna.org. 5 NS ns-908.awsdns-49.net.
vicugna.org. 5 NS ns-1355.awsdns-41.org.
vicugna.org. 5 NS ns-1899.awsdns-45.co.uk.
vicugna.org. 5 NS ns-97.awsdns-12.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0