Apex domains cannot have CNAME records.
Question and response
Question
dig aumanaged.com. NS
Answer
aumanaged.com. 5 NS nssyd01.aumanaged.com.
aumanaged.com. 5 NS nsdal01.aumanaged.com.
aumanaged.com. 5 NS nssyd02.aumanaged.com.
Authority
The response has no authority records.
Additional
nsdal01.aumanaged.com. 5 A 128.199.165.252
nssyd01.aumanaged.com. 5 A 182.160.136.154
nssyd02.aumanaged.com. 5 A 182.160.160.175
nsdal01.aumanaged.com. 5 AAAA 2607:f198:1000:2:0:0:0:55
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0