Apex domains cannot have CNAME records.
Question and response
Question
dig digitalocean.com. NS
Answer
digitalocean.com. 2 NS kim.ns.cloudflare.com.
digitalocean.com. 2 NS walt.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0