Apex domains cannot have CNAME records.
Question and response
Question
dig hubspot.net. NS
Answer
hubspot.net. 5 NS jerry.ns.cloudflare.com.
hubspot.net. 5 NS yolanda.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0