Apex domains cannot have CNAME records.
Question and response
Question
dig ms-acdc.office.com. NS
Answer
ms-acdc.office.com. 5 NS ns1-ms-acdc.office.com.
ms-acdc.office.com. 5 NS ns4-ms-acdc.office.com.
ms-acdc.office.com. 5 NS ns3-ms-acdc.office.com.
ms-acdc.office.com. 5 NS ns2-ms-acdc.office.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0