Apex domains cannot have CNAME records.
Question and response
Question
dig asta-uk.com. NS
Answer
asta-uk.com. 5 NS ns56.domaincontrol.com.
asta-uk.com. 5 NS ns55.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0