Apex domains cannot have CNAME records.
Question and response
Question
dig eftel.com. NS
Answer
eftel.com. 5 NS ns0.eftel.com.
eftel.com. 5 NS ns2.eftel.com.
eftel.com. 5 NS ns1.eftel.com.
Authority
The response has no authority records.
Additional
ns0.eftel.com. 5 A 203.134.64.67
ns1.eftel.com. 5 A 203.134.153.66
ns2.eftel.com. 5 A 203.134.153.66
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0