Apex domains cannot have CNAME records.
Question and response
Question
dig bl.ink. NS
Answer
bl.ink. 5 NS ns-1434.awsdns-51.org.
bl.ink. 5 NS ns-370.awsdns-46.com.
bl.ink. 5 NS ns-610.awsdns-12.net.
bl.ink. 5 NS ns-1861.awsdns-40.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0