Apex domains cannot have CNAME records.
Question and response
Question
dig uisp.com. NS
Answer
uisp.com. 5 NS ns-1009.awsdns-62.net.
uisp.com. 5 NS ns-1142.awsdns-14.org.
uisp.com. 5 NS ns-1858.awsdns-40.co.uk.
uisp.com. 5 NS ns-260.awsdns-32.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0