Apex domains cannot have CNAME records.
Question and response
Question
dig ns1.ukservers.com. NS
Answer
ns1.ukservers.com. 5 NS ns1.ukservers.com.
Authority
The response has no authority records.
Additional
ns1.ukservers.com. 5 A 94.229.73.251
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0