Apex domains cannot have CNAME records.
Question and response
Question
dig stoverjenkins.com. NS
Answer
stoverjenkins.com. 5 NS ns-1863.awsdns-40.co.uk.
stoverjenkins.com. 5 NS ns-1743.awsdns-25.co.uk.
stoverjenkins.com. 5 NS ns-162.awsdns-20.com.
stoverjenkins.com. 5 NS ns-958.awsdns-55.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0