Apex domains cannot have CNAME records.
Question and response
Question
dig my-hosts.co.uk. NS
Answer
my-hosts.co.uk. 5 NS dns1.zoneedit.com.
my-hosts.co.uk. 5 NS dns2.zoneedit.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0