Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-58.co.uk. NS
Answer
awsdns-58.co.uk. 5 NS g-ns-954.awsdns-58.co.uk.
awsdns-58.co.uk. 5 NS g-ns-1854.awsdns-58.co.uk.
awsdns-58.co.uk. 5 NS g-ns-378.awsdns-58.co.uk.
awsdns-58.co.uk. 5 NS g-ns-1533.awsdns-58.co.uk.
Authority
The response has no authority records.
Additional
g-ns-378.awsdns-58.co.uk. 5 A 205.251.193.122
g-ns-954.awsdns-58.co.uk. 5 A 205.251.195.186
g-ns-1533.awsdns-58.co.uk. 5 A 205.251.197.253
g-ns-1854.awsdns-58.co.uk. 5 A 205.251.199.62
g-ns-378.awsdns-58.co.uk. 5 AAAA 2600:9000:5301:7a00:0:0:0:1
g-ns-954.awsdns-58.co.uk. 5 AAAA 2600:9000:5303:ba00:0:0:0:1
g-ns-1533.awsdns-58.co.uk. 5 AAAA 2600:9000:5305:fd00:0:0:0:1
g-ns-1854.awsdns-58.co.uk. 5 AAAA 2600:9000:5307:3e00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0