Apex domains cannot have CNAME records.
Question and response
Question
dig ctrls.in. NS
Answer
ctrls.in. 4 NS ns20.ctrls.in.
ctrls.in. 4 NS ns1.ctrls.in.
ctrls.in. 4 NS ns2.ctrls.in.
Authority
The response has no authority records.
Additional
ns20.ctrls.in. 4 A 45.249.109.172
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0