Apex domains cannot have CNAME records.
Question and response
Question
dig star.net.uk. NS
Answer
star.net.uk. 5 NS dns0.star.co.uk.
star.net.uk. 5 NS dns1.star.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0