Apex domains cannot have CNAME records.
Question and response
Question
dig robiblog.com. NS
Answer
robiblog.com. 5 NS ns2.robiblog.com.
robiblog.com. 5 NS ns1.robiblog.com.
Authority
The response has no authority records.
Additional
ns1.robiblog.com. 5 A 208.115.245.26
ns2.robiblog.com. 5 A 208.115.245.26
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0