Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-09.co.uk. NS
Answer
awsdns-09.co.uk. 5 NS g-ns-329.awsdns-09.co.uk.
awsdns-09.co.uk. 5 NS g-ns-1805.awsdns-09.co.uk.
awsdns-09.co.uk. 5 NS g-ns-1484.awsdns-09.co.uk.
awsdns-09.co.uk. 5 NS g-ns-905.awsdns-09.co.uk.
Authority
The response has no authority records.
Additional
g-ns-329.awsdns-09.co.uk. 5 A 205.251.193.73
g-ns-905.awsdns-09.co.uk. 5 A 205.251.195.137
g-ns-1484.awsdns-09.co.uk. 5 A 205.251.197.204
g-ns-1805.awsdns-09.co.uk. 5 A 205.251.199.13
g-ns-329.awsdns-09.co.uk. 5 AAAA 2600:9000:5301:4900:0:0:0:1
g-ns-905.awsdns-09.co.uk. 5 AAAA 2600:9000:5303:8900:0:0:0:1
g-ns-1484.awsdns-09.co.uk. 5 AAAA 2600:9000:5305:cc00:0:0:0:1
g-ns-1805.awsdns-09.co.uk. 5 AAAA 2600:9000:5307:d00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0