Apex domains cannot have CNAME records.
Question and response
Question
dig universal-cloud.com. NS
Answer
universal-cloud.com. 5 NS ns-419.awsdns-52.com.
universal-cloud.com. 5 NS ns-1118.awsdns-11.org.
universal-cloud.com. 5 NS ns-981.awsdns-58.net.
universal-cloud.com. 5 NS ns-1783.awsdns-30.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0