Apex domains cannot have CNAME records.
Question and response
Question
dig manage-subscription.com. NS
Answer
manage-subscription.com. 3 NS ns-1774.awsdns-29.co.uk.
manage-subscription.com. 3 NS ns-881.awsdns-46.net.
manage-subscription.com. 3 NS ns-214.awsdns-26.com.
manage-subscription.com. 3 NS ns-1234.awsdns-26.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0