Apex domains cannot have CNAME records.
Question and response
Question
dig vtscloud.io. NS
Answer
vtscloud.io. 2 NS ns-1941.awsdns-50.co.uk.
vtscloud.io. 2 NS ns-61.awsdns-07.com.
vtscloud.io. 2 NS ns-998.awsdns-60.net.
vtscloud.io. 2 NS ns-1435.awsdns-51.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0