Apex domains cannot have CNAME records.
Question and response
Question
dig bunnydns.com. NS
Answer
bunnydns.com. 5 NS ns1.bunnydns.com.
bunnydns.com. 5 NS ns2.bunnydns.com.
bunnydns.com. 5 NS ns3.bunnydns.com.
Authority
The response has no authority records.
Additional
ns1.bunnydns.com. 5 A 157.53.226.1
ns2.bunnydns.com. 5 A 109.104.147.1
ns3.bunnydns.com. 5 A 91.200.176.1
ns1.bunnydns.com. 5 AAAA 2607:f740:e00c:0:0:0:0:1
ns2.bunnydns.com. 5 AAAA 2400:52e0:fff2:0:0:0:0:1
ns3.bunnydns.com. 5 AAAA 2400:52e0:fff0:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0