Apex domains cannot have CNAME records.
Question and response
Question
dig tatacommunications.com. NS
Answer
tatacommunications.com. 5 NS ns2.tatacommunications.com.
tatacommunications.com. 5 NS ns1.tatacommunications.com.
Authority
The response has no authority records.
Additional
ns1.tatacommunications.com. 5 A 121.244.76.80
ns2.tatacommunications.com. 5 A 121.243.33.174
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0