Apex domains cannot have CNAME records.
Question and response
Question
dig atspagespeed.com. NS
Answer
atspagespeed.com. 4 NS ns-76.awsdns-09.com.
atspagespeed.com. 4 NS ns-1408.awsdns-48.org.
atspagespeed.com. 4 NS ns-380.awsdns-47.com.
atspagespeed.com. 4 NS ns-1952.awsdns-52.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0