Apex domains cannot have CNAME records.
Question and response
Question
dig windmillcache.com. NS
Answer
windmillcache.com. 3 NS ns2.windmillcache.com.
windmillcache.com. 3 NS ns1.windmillcache.com.
Authority
The response has no authority records.
Additional
ns1.windmillcache.com. 3 A 158.69.203.90
ns2.windmillcache.com. 3 A 51.79.35.101
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0