Apex domains cannot have CNAME records.
Question and response
Question
dig phishme.co.uk. NS
Answer
phishme.co.uk. 5 NS ns-860.awsdns-43.net.
phishme.co.uk. 5 NS ns-109.awsdns-13.com.
phishme.co.uk. 5 NS ns-1890.awsdns-44.co.uk.
phishme.co.uk. 5 NS ns-1474.awsdns-56.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0