Apex domains cannot have CNAME records.
Question and response
Question
dig clinicasy.com. NS
Answer
clinicasy.com. 5 NS ns2.clinicasy.com.
clinicasy.com. 5 NS ns3.clinicasy.com.
Authority
The response has no authority records.
Additional
ns2.clinicasy.com. 5 A 66.181.38.202
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0