Apex domains cannot have CNAME records.
Question and response
Question
dig spgo.io. NS
Answer
spgo.io. 5 NS ns-277.awsdns-34.com.
spgo.io. 5 NS ns-1748.awsdns-26.co.uk.
spgo.io. 5 NS ns-1380.awsdns-44.org.
spgo.io. 5 NS ns-678.awsdns-20.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0