Apex domains cannot have CNAME records.
Question and response
Question
dig xtremetennis.org. NS
Answer
xtremetennis.org. 4 NS ns-1811.awsdns-34.co.uk.
xtremetennis.org. 4 NS ns-626.awsdns-14.net.
xtremetennis.org. 4 NS ns-1025.awsdns-00.org.
xtremetennis.org. 4 NS ns-1184.awsdns-20.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0