Apex domains cannot have CNAME records.
Question and response
Question
dig plateau.com. NS
Answer
plateau.com. 5 NS ns1.sap.net.
plateau.com. 5 NS ns4.sap.asia.
plateau.com. 5 NS ns3.sap.com.
plateau.com. 5 NS ns2.sap.de.
Authority
The response has no authority records.
Additional
ns1.sap.net. 2 A 193.46.3.53
ns2.sap.de. 2 A 195.253.90.7
ns3.sap.com. 2 A 67.221.252.72
ns4.sap.asia. 2 A 169.145.112.153
ns2.sap.de. 2 AAAA 2a01:5b0:12:0:0:0:0:7
ns3.sap.com. 2 AAAA 2607:fae0:f00d:0:0:0:0:72
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0