Apex domains cannot have CNAME records.
Question and response
Question
dig support.mikrotec.com. NS
Answer
support.mikrotec.com. 5 NS ns2.mis.net.
support.mikrotec.com. 5 NS ns1.mis.net.
Authority
The response has no authority records.
Additional
ns1.mis.net. 5 A 69.176.0.36
ns2.mis.net. 5 A 74.214.190.4
ns1.mis.net. 5 AAAA 2607:c00:1a:1041:0:0:0:36
ns2.mis.net. 5 AAAA 2607:c00:1b:1049:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0