emb.bigcommerce.com has no CNAME records.
Question and response
Question
dig emb.bigcommerce.com. NS
Answer
The response has no answer records.
Authority
bigcommerce.com. 3099 SOA dns1.p04.nsone.net. hostmaster.nsone.net. 1648762509 43200 7200 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0