Apex domains cannot have CNAME records.
Question and response
Question
dig sleepysquirrel.com. NS
Answer
sleepysquirrel.com. 5 NS ns2.sleepysquirrel.com.
sleepysquirrel.com. 5 NS ns1.sleepysquirrel.com.
Authority
The response has no authority records.
Additional
ns1.sleepysquirrel.com. 5 A 144.217.68.99
ns2.sleepysquirrel.com. 5 A 144.172.126.87
ns1.sleepysquirrel.com. 5 AAAA 2607:5300:203:63:0:0:0:63
ns2.sleepysquirrel.com. 5 AAAA 2602:fe64:8:0:0:0:0:16
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0