Apex domains cannot have CNAME records.
Question and response
Question
dig prod.hosts.ooklaserver.net. NS
Answer
prod.hosts.ooklaserver.net. 5 NS ns-1882.awsdns-43.co.uk.
prod.hosts.ooklaserver.net. 5 NS ns-1211.awsdns-23.org.
prod.hosts.ooklaserver.net. 5 NS ns-363.awsdns-45.com.
prod.hosts.ooklaserver.net. 5 NS ns-861.awsdns-43.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0