Apex domains cannot have CNAME records.
Question and response
Question
dig bigbytesystems.com. NS
Answer
bigbytesystems.com. 2 NS ns3.bigbytesystems.com.
bigbytesystems.com. 2 NS ns1.bigbytesystems.com.
bigbytesystems.com. 2 NS ns2.bigbytesystems.com.
bigbytesystems.com. 2 NS ns4.bigbytesystems.com.
Authority
The response has no authority records.
Additional
ns1.bigbytesystems.com. 2 A 199.21.74.66
ns2.bigbytesystems.com. 2 A 199.21.74.67
ns3.bigbytesystems.com. 2 A 199.21.74.68
ns4.bigbytesystems.com. 2 A 199.21.74.69
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0