Apex domains cannot have CNAME records.
Question and response
Question
dig blackspider.com. NS
Answer
blackspider.com. 5 NS ns-g.blackspider.com.
blackspider.com. 5 NS ns-r.blackspider.com.
blackspider.com. 5 NS ns-a.blackspider.com.
Authority
The response has no authority records.
Additional
ns-a.blackspider.com. 5 A 85.115.52.190
ns-g.blackspider.com. 5 A 208.87.233.190
ns-r.blackspider.com. 5 A 116.50.60.190
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0