Apex domains cannot have CNAME records.
Question and response
Question
dig sedoparking.com. NS
Answer
sedoparking.com. 5 NS ns-1830.awsdns-36.co.uk.
sedoparking.com. 5 NS ns-802.awsdns-36.net.
sedoparking.com. 5 NS ns-48.awsdns-06.com.
sedoparking.com. 5 NS ns-1057.awsdns-04.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0