Apex domains cannot have CNAME records.
Question and response
Question
dig serverplan.com. NS
Answer
serverplan.com. 5 NS ns1.serverplan.com.
serverplan.com. 5 NS ns2.serverplan.com.
Authority
The response has no authority records.
Additional
ns1.serverplan.com. 5 A 185.81.7.131
ns2.serverplan.com. 5 A 93.95.222.131
ns1.serverplan.com. 5 AAAA 2a02:24b8:3:1783:0:0:0:0
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0