smtp-cluster.jay.net has no CNAME records.
Question and response
Question
dig smtp-cluster.jay.net. NS
Answer
The response has no answer records.
Authority
jay.net. 3600 SOA ns.jay.net. hostmaster.jay.net. 2025102701 14400 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0