set.sobanus.com has no CNAME records.
Question and response
Question
dig set.sobanus.com. NS
Answer
The response has no answer records.
Authority
sobanus.com. 2462 SOA dns.sobanus.com. hostmaster.sobanus.com. 1648442499 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0