Apex domains cannot have CNAME records.
Question and response
Question
dig managed-otrs.com. NS
Answer
managed-otrs.com. 5 NS ns11.managed-otrs.com.
managed-otrs.com. 5 NS ns12.managed-otrs.com.
managed-otrs.com. 5 NS ns10.managed-otrs.com.
Authority
The response has no authority records.
Additional
ns10.managed-otrs.com. 5 A 116.202.80.40
ns11.managed-otrs.com. 5 A 148.251.67.123
ns12.managed-otrs.com. 5 A 95.216.61.234
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0