Apex domains cannot have CNAME records.
Question and response
Question
dig rapidswitch.com. NS
Answer
rapidswitch.com. 5 NS ns3.rapidswitch.com.
rapidswitch.com. 5 NS ns2.rapidswitch.com.
rapidswitch.com. 5 NS ns1.rapidswitch.com.
Authority
The response has no authority records.
Additional
ns1.rapidswitch.com. 5 A 87.117.237.205
ns2.rapidswitch.com. 5 A 87.117.237.66
ns3.rapidswitch.com. 5 A 84.22.168.154
ns1.rapidswitch.com. 5 AAAA 2001:1b40:f000:41:0:0:0:4
ns2.rapidswitch.com. 5 AAAA 2001:1b40:f000:42:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0