Apex domains cannot have CNAME records.
Question and response
Question
dig vista02.com. NS
Answer
vista02.com. 5 NS ns-1504.awsdns-60.org.
vista02.com. 5 NS ns-1213.awsdns-23.org.
vista02.com. 5 NS ns-1479.awsdns-56.org.
vista02.com. 5 NS ns-1571.awsdns-04.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0