Apex domains cannot have CNAME records.
Question and response
Question
dig iplanisp.com. NS
Answer
iplanisp.com. 5 NS dns3.iplanisp.com.
iplanisp.com. 5 NS dns2.iplanisp.com.
iplanisp.com. 5 NS dns1.iplanisp.com.
Authority
The response has no authority records.
Additional
dns1.iplanisp.com. 5 A 162.159.26.103
dns2.iplanisp.com. 5 A 190.2.2.250
dns3.iplanisp.com. 5 A 162.159.27.69
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0