Apex domains cannot have CNAME records.
Question and response
Question
dig knottberryfarm.com. NS
Answer
knottberryfarm.com. 5 NS ns-1679.awsdns-17.co.uk.
knottberryfarm.com. 5 NS ns-470.awsdns-58.com.
knottberryfarm.com. 5 NS ns-18.awsdns-02.com.
knottberryfarm.com. 5 NS ns-1193.awsdns-21.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0