Apex domains cannot have CNAME records.
Question and response
Question
dig srv1.com. NS
Answer
srv1.com. 5 NS rita.ns.cloudflare.com.
srv1.com. 5 NS jay.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0