Apex domains cannot have CNAME records.
Question and response
Question
dig thomasmonnington.com. NS
Answer
thomasmonnington.com. 5 NS ns-309.awsdns-38.com.
thomasmonnington.com. 5 NS ns-1376.awsdns-44.org.
thomasmonnington.com. 5 NS ns-767.awsdns-31.net.
thomasmonnington.com. 5 NS ns-1566.awsdns-03.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0