site1.exch580.serverdata.net has no CNAME records.
Question and response
Question
dig site1.exch580.serverdata.net. NS
Answer
The response has no answer records.
Authority
exch580.serverdata.net. 3259 SOA ns2.serverdata.net. hostmaster.serverdata.net. 2025121915 3600 1800 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0