custmx.cscdns.net has no CNAME records.
Question and response
Question
dig custmx.cscdns.net. NS
Answer
The response has no answer records.
Authority
cscdns.net. 10800 SOA udns1.cscdns.net. hostmaster.cscdns.net. 2007080919 28800 7200 604800 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0