Apex domains cannot have CNAME records.
Question and response
Question
dig us-langley-1.oci.oraclegoviaas.com. NS
Answer
us-langley-1.oci.oraclegoviaas.com. 5 NS ns2.p200.dns.us-langley-1.oci.oraclegoviaas.com.
us-langley-1.oci.oraclegoviaas.com. 5 NS ns1.p200.dns.us-langley-1.oci.oraclegoviaas.com.
us-langley-1.oci.oraclegoviaas.com. 5 NS ns3.p200.dns.us-langley-1.oci.oraclegoviaas.com.
Authority
The response has no authority records.
Additional
ns1.p200.dns.us-langley-1.oci.oraclegoviaas.com. 5 A 155.248.11.248
ns2.p200.dns.us-langley-1.oci.oraclegoviaas.com. 5 A 155.248.13.194
ns3.p200.dns.us-langley-1.oci.oraclegoviaas.com. 5 A 155.248.12.219
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0