Apex domains cannot have CNAME records.
Question and response
Question
dig phpbbargentina.com. NS
Answer
phpbbargentina.com. 4 NS ns-1251.awsdns-28.org.
phpbbargentina.com. 4 NS ns-1869.awsdns-41.co.uk.
phpbbargentina.com. 4 NS ns-917.awsdns-50.net.
phpbbargentina.com. 4 NS ns-1440.awsdns-52.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0