spamfilter.sc2000.net has no CNAME records.
Question and response
Question
dig spamfilter.sc2000.net. NS
Answer
The response has no answer records.
Authority
sc2000.net. 3600 SOA ns1.sc2000.net. stevem.sc2000.net. 2026012902 3600 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0