Apex domains cannot have CNAME records.
Question and response
Question
dig annagreenacre.com. NS
Answer
annagreenacre.com. 5 NS ns-448.awsdns-56.com.
annagreenacre.com. 5 NS ns-1671.awsdns-16.co.uk.
annagreenacre.com. 5 NS ns-423.awsdns-52.com.
annagreenacre.com. 5 NS ns-501.awsdns-62.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0