Apex domains cannot have CNAME records.
Question and response
Question
dig ms.com. NS
Answer
ms.com. 5 NS ext-ns5.morganstanley.net.
ms.com. 5 NS ext-ns1.morganstanley.net.
ms.com. 5 NS ext-ns3.morganstanley.net.
ms.com. 5 NS ext-ns12.morganstanley.net.
ms.com. 5 NS ext-ns10.morganstanley.net.
ms.com. 5 NS ext-ns8.morganstanley.net.
Authority
The response has no authority records.
Additional
ext-ns1.morganstanley.net. 5 A 198.51.44.1
ext-ns3.morganstanley.net. 5 A 198.51.45.1
ext-ns5.morganstanley.net. 5 A 198.51.44.65
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0