Apex domains cannot have CNAME records.
Question and response
Question
dig ci.nttsvc.com. NS
Answer
ci.nttsvc.com. 5 NS ns0.ci.nttsvc.com.
ci.nttsvc.com. 5 NS ns1.ci.nttsvc.com.
Authority
The response has no authority records.
Additional
ns0.ci.nttsvc.com. 5 A 213.130.53.8
ns1.ci.nttsvc.com. 5 A 213.198.28.138
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0