Apex domains cannot have CNAME records.
Question and response
Question
dig ums-dns-salesforce.com. NS
Answer
ums-dns-salesforce.com. 5 NS ns02.ums-dns-salesforce.com.
ums-dns-salesforce.com. 5 NS ns03.ums-dns-salesforce.com.
ums-dns-salesforce.com. 5 NS ns04.ums-dns-salesforce.com.
ums-dns-salesforce.com. 5 NS ns01.ums-dns-salesforce.com.
Authority
The response has no authority records.
Additional
ns01.ums-dns-salesforce.com. 5 A 104.225.42.1
ns02.ums-dns-salesforce.com. 5 A 104.225.42.65
ns03.ums-dns-salesforce.com. 5 A 104.225.42.129
ns04.ums-dns-salesforce.com. 5 A 104.225.42.193
ns01.ums-dns-salesforce.com. 5 AAAA 2607:f740:e048:0:0:0:0:1
ns02.ums-dns-salesforce.com. 5 AAAA 2607:f740:e048:4:0:0:0:1
ns03.ums-dns-salesforce.com. 5 AAAA 2607:f740:e048:8:0:0:0:1
ns04.ums-dns-salesforce.com. 5 AAAA 2607:f740:e048:c:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0