Apex domains cannot have CNAME records.
Question and response
Question
dig sdncommunications.com. NS
Answer
sdncommunications.com. 1 NS ns5.sdncommunications.com.
sdncommunications.com. 1 NS ns2.sdncommunications.com.
sdncommunications.com. 1 NS ns1.sdncommunications.com.
Authority
The response has no authority records.
Additional
ns1.sdncommunications.com. 2 A 66.231.7.62
ns2.sdncommunications.com. 2 A 66.231.0.62
ns5.sdncommunications.com. 2 A 45.33.28.12
ns1.sdncommunications.com. 2 AAAA 2607:fc00:0:1e:0:0:0:10
ns2.sdncommunications.com. 2 AAAA 2607:fc00:0:16:0:0:0:11
ns5.sdncommunications.com. 2 AAAA 2600:3c00:0:0:f03c:94ff:fe60:9bae
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0