Apex domains cannot have CNAME records.
Question and response
Question
dig prod.101domain.com. NS
Answer
prod.101domain.com. 5 NS NS1.101domain.com.
prod.101domain.com. 5 NS NS2.101domain.com.
prod.101domain.com. 5 NS NS5.101domain.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0