Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-30.co.uk. NS
Answer
awsdns-30.co.uk. 5 NS g-ns-926.awsdns-30.co.uk.
awsdns-30.co.uk. 5 NS g-ns-350.awsdns-30.co.uk.
awsdns-30.co.uk. 5 NS g-ns-1826.awsdns-30.co.uk.
awsdns-30.co.uk. 5 NS g-ns-1505.awsdns-30.co.uk.
Authority
The response has no authority records.
Additional
g-ns-350.awsdns-30.co.uk. 5 A 205.251.193.94
g-ns-926.awsdns-30.co.uk. 5 A 205.251.195.158
g-ns-1505.awsdns-30.co.uk. 5 A 205.251.197.225
g-ns-1826.awsdns-30.co.uk. 5 A 205.251.199.34
g-ns-350.awsdns-30.co.uk. 5 AAAA 2600:9000:5301:5e00:0:0:0:1
g-ns-926.awsdns-30.co.uk. 5 AAAA 2600:9000:5303:9e00:0:0:0:1
g-ns-1505.awsdns-30.co.uk. 5 AAAA 2600:9000:5305:e100:0:0:0:1
g-ns-1826.awsdns-30.co.uk. 5 AAAA 2600:9000:5307:2200:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0